This calculator is provided for informational and educational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare professional before making any medical decisions. The results from this calculator should be used as a reference guide only and not as the sole basis for clinical decisions. Dengue is a dynamic illness – this assessment reflects the clinical state at one point in time and must be repeated as the illness progresses.
Dengue Severity Calculator
Structured clinical assessment tool based on WHO 2009 revised dengue classification. Evaluate all 7 dengue warning signs, assess severe dengue criteria including dengue shock syndrome and organ impairment, and receive evidence-based management guidance for dengue fever triage and hospital admission decisions.
Fever plus 2 or more of the following:
Any one of these signs requires hospital admission:
Any one of these features = Severe Dengue:
WHO 2009 Dengue Severity Classification Reference
| Classification | Key Criteria | Management | Risk Level |
|---|---|---|---|
| Dengue (No Warning Signs) | Fever plus 2 or more: nausea/vomiting, rash, aches, positive tourniquet test, leukopenia. No warning signs present. | Home care with daily follow-up. Oral rehydration, paracetamol (not NSAIDs). Written warning sign instructions. | Low Risk |
| Dengue with Warning Signs | Any dengue case with one or more of the 7 WHO warning signs present. | Hospital admission. IV fluid therapy. Close monitoring of vitals and haematocrit every 4-6 hours. Platelet count monitoring. | Moderate-High Risk |
| Severe Dengue | Severe plasma leakage (shock or respiratory distress), severe bleeding, or severe organ impairment (liver, CNS, heart, kidney). | Emergency hospital care. Immediate IV fluid resuscitation for shock. ICU-level monitoring. Specialist team involvement. | Critical – Emergency |
| Dengue Shock Syndrome | Pulse pressure below 20 mmHg (systolic minus diastolic), or age-appropriate hypotension, with rising haematocrit confirming plasma leakage. | Isotonic crystalloid 10 ml/kg bolus over 15-30 minutes. Reassess every 15-30 minutes. Repeat bolus if no improvement. Escalate to colloid if unresponsive. | Critical – Emergency |
All 7 WHO Dengue Warning Signs – Clinical Criteria Detail
| Warning Sign | Clinical Description | Pathophysiological Basis |
|---|---|---|
| 1. Abdominal Pain or Tenderness | Persistent or severe abdominal pain, or tenderness on palpation of the abdomen, especially the right upper quadrant and epigastrium | Dengue hepatitis causing hepatic pain; ascites from plasma leakage into the peritoneal cavity; retroperitoneal fluid accumulation |
| 2. Persistent Vomiting | Vomiting that prevents adequate oral fluid intake; clinically defined as inability to keep fluids down due to repeated vomiting episodes | Gastric irritation from dengue-related gastritis; dehydration exacerbating nausea; direct effect of dengue viraemia on the gastrointestinal tract |
| 3. Clinical Fluid Accumulation | Clinical or radiological evidence of fluid in body cavities: ascites (abdominal fluid), pleural effusion (fluid around lungs), or pericardial effusion (fluid around heart) | Increased vascular permeability causing plasma leakage from the intravascular to extravascular compartment, accumulating in potential body spaces |
| 4. Mucosal Bleeding | Spontaneous bleeding from mucosal surfaces: gum bleeding on minimal provocation, epistaxis (nosebleed), conjunctival haemorrhage (bleeding in the eye) | Dengue-associated thrombocytopenia and platelet dysfunction combined with capillary fragility from vascular endothelial damage |
| 5. Lethargy or Restlessness | Marked lethargy, unusual drowsiness, difficulty waking, or paradoxical agitation or restlessness, particularly in children | Reduced cerebral perfusion from plasma leakage and early circulatory compromise; direct dengue effect on the central nervous system; hepatic encephalopathy from dengue hepatitis |
| 6. Liver Enlargement greater than 2 cm | Hepatomegaly with the liver palpable more than 2 cm below the right costal margin on clinical examination | Dengue hepatitis causing hepatocyte injury and liver swelling; Kupffer cell activation from dengue viraemia; hepatic inflammation |
| 7. Rising Haematocrit with Rapid Platelet Drop | Concurrent 20% or more rise in haematocrit above baseline AND a rapid fall in platelet count, often to below 100,000 per microlitre | The haematocrit rise reflects plasma leakage causing haemoconcentration; the platelet drop reflects bone marrow suppression from dengue viraemia and peripheral platelet consumption |
Dengue Laboratory Reference Values and Severity Thresholds
| Parameter | Value / Range | Clinical Significance in Dengue | Status |
|---|---|---|---|
| Platelet Count | Above 100,000 x10^3/uL | Normal range; dengue may show mild reduction. Monitor trend. | Normal |
| Platelet Count | 50,000 – 100,000 x10^3/uL | Mild to moderate thrombocytopenia. Increased monitoring frequency. Dengue with warning signs if concurrent with haematocrit rise. | Mild-Moderate |
| Platelet Count | 20,000 – 50,000 x10^3/uL | Moderate to severe thrombocytopenia. High risk of bleeding with trauma or procedures. Consider inpatient monitoring. | Severe |
| Platelet Count | Below 20,000 x10^3/uL | Profound thrombocytopenia. Risk of spontaneous bleeding. Platelet transfusion only if active significant bleeding – not prophylactically. | Critical |
| Haematocrit Rise | Below 10% above baseline | Minimal plasma leakage. Monitor closely if approaching defervescence. | Minimal |
| Haematocrit Rise | 10% – 20% above baseline | Moderate haemoconcentration. Increasing risk of plasma leakage. Ensure adequate oral hydration and close follow-up. | Moderate |
| Haematocrit Rise | 20% or more above baseline | Significant plasma leakage – WHO Warning Sign. Requires hospitalisation and IV fluid management. | Warning Sign |
| White Cell Count (WBC) | Below 4,000 x10^3/uL | Leukopenia is a diagnostic criterion for dengue (not a severity marker). Common in the febrile phase. | Low (expected) |
| Liver Enzymes (AST/ALT) | Normal to 5 times upper limit | Mild elevation common in dengue. Monitor trend. | Mild |
| Liver Enzymes (AST/ALT) | Above 1000 IU/L | Severe dengue hepatitis – this alone meets Severe Dengue criteria regardless of other features. | Severe Dengue |
| Pulse Pressure | Below 20 mmHg | Dengue Shock Syndrome – compensated shock with plasma leakage. Urgent fluid resuscitation required. | Shock |
About This Dengue Severity Calculator
This dengue severity calculator is designed for healthcare professionals, medical students, and trained clinicians who need a structured, systematic tool for classifying dengue severity at the point of care. It computes WHO 2009 dengue severity classification by guiding the user through evaluation of dengue diagnostic criteria, all seven WHO dengue warning signs, severe dengue features including dengue shock syndrome, and laboratory parameters including haematocrit rise and platelet count severity – producing an evidence-based severity classification and management guidance in real time.
The calculator applies the World Health Organization 2009 revised dengue guidelines, which classify dengue into three actionable tiers: dengue without warning signs (suitable for home management with daily follow-up), dengue with warning signs (requires hospital admission and IV fluid monitoring), and severe dengue (requires emergency hospital treatment). The severe dengue tier is further subdivided by pathway: severe plasma leakage (dengue shock syndrome with pulse pressure below 20 mmHg or hypotension, or fluid accumulation with respiratory distress), severe bleeding, and severe organ impairment (liver AST or ALT 1000 IU/L or above, impaired consciousness from dengue encephalopathy or encephalitis, or other organ failure). The haematocrit rise calculator identifies the 20% threshold that constitutes a dengue warning sign for plasma leakage.
Using this dengue clinical assessment tool reduces the risk of missing warning signs during high-volume triage, particularly during the critical defervescence period when patients may appear clinically stable while plasma leakage is progressing. The Dengue Severity Reference tab provides a complete WHO 2009 classification table; the Warning Signs Clinical Criteria tab details the pathophysiological basis of each of the seven warning signs; and the Lab Values Reference tab displays dengue thrombocytopenia severity thresholds and haematocrit rise interpretation ranges. All assessments should be performed by a qualified clinician and repeated as the illness evolves – dengue is a dynamic disease, and a single assessment does not substitute for continuous clinical monitoring.
Dengue Severity Calculator – Complete Clinical Guide to WHO 2009 Classification, Warning Signs, and Patient Management
Dengue fever is one of the most significant mosquito-borne viral diseases in the world, affecting an estimated 390 million people annually across more than 100 countries. The disease is caused by any of four serotypes of the dengue virus (DENV-1 through DENV-4), transmitted primarily by the Aedes aegypti and Aedes albopictus mosquitoes. Accurate severity assessment is critical because dengue can progress rapidly from a mild febrile illness to severe dengue with life-threatening complications including plasma leakage, haemorrhage, and organ impairment.
This dengue severity calculator is built on the World Health Organization (WHO) 2009 revised classification system, which replaced the older 1997 classification and is now widely used in clinical practice globally. Understanding how to apply this classification – and recognising the warning signs that require immediate medical attention – can be the difference between safe outpatient monitoring and timely hospital admission that saves a life.
The WHO 2009 Dengue Classification System
The WHO 2009 guidelines introduced a three-tier classification of dengue that better reflects the clinical spectrum of the disease and guides management decisions at each stage. The three categories are: Dengue (without warning signs), Dengue with Warning Signs, and Severe Dengue.
This revised classification was developed following extensive field experience showing that the older categories (dengue fever, dengue haemorrhagic fever grades I-IV, and dengue shock syndrome) did not adequately guide clinical decision-making, particularly in identifying patients at risk of deterioration before they developed severe disease. The 2009 framework emphasises prospective monitoring for warning signs as the key triage tool.
Dengue with Warning Signs: Any dengue case with one or more of the seven WHO warning signs. Requires inpatient observation and intravenous fluid support in many cases.
Severe Dengue: Severe plasma leakage with shock or fluid accumulation with respiratory distress, severe bleeding, or severe organ impairment. Requires emergency treatment in a hospital with intensive care capability.
The Seven WHO Dengue Warning Signs
Recognising the seven warning signs defined by the WHO is the cornerstone of dengue triage. These signs typically appear around the time of defervescence – when the fever breaks, usually between days 3 and 7 of illness. This is a critical and deceptive period because patients may appear to be improving while actually entering the most dangerous phase of disease.
The seven warning signs are: abdominal pain or tenderness; persistent vomiting; clinical fluid accumulation (ascites, pleural effusion, or pericardial effusion detected clinically or on imaging); mucosal bleeding; lethargy or restlessness; liver enlargement greater than 2 cm; and a rise in haematocrit concurrent with a rapid decrease in platelet count. Each of these signs reflects a specific pathophysiological process that increases the risk of progression to severe dengue.
Warning signs most commonly appear when the fever breaks, typically between days 3 and 7 of illness. Paradoxically, patients may feel subjectively better as the fever subsides, masking the onset of plasma leakage. Clinicians and caregivers must be vigilant during this period even when the patient appears to be improving.
Understanding Severe Dengue Criteria
Severe dengue is defined by the presence of one or more of three major categories of severe manifestation. The first is severe plasma leakage leading to dengue shock syndrome (narrowed pulse pressure below 20 mmHg, or hypotension for age) or respiratory distress from fluid accumulation in the pleural space or abdomen. The second is severe bleeding as assessed by the treating clinician. The third is severe organ involvement – including liver injury (AST or ALT of 1000 IU/L or above), central nervous system manifestations such as impaired consciousness, or other organ failures affecting the heart, kidneys, or other systems.
Understanding that these three pathways represent distinct clinical syndromes helps guide both diagnosis and management. A patient in dengue shock requires aggressive but carefully measured fluid resuscitation, whereas a patient with impaired consciousness requires neurological assessment and investigation for dengue encephalitis or encephalopathy. One-size-fits-all management is inappropriate in severe dengue.
Severe Bleeding: Clinically significant haemorrhage judged by the treating physician to require intervention or that is haemodynamically significant.
Severe Organ Impairment: Liver: AST or ALT 1000 IU/L or above. CNS: Impaired consciousness, dengue encephalitis or encephalopathy. Heart: myocarditis. Kidneys: acute kidney injury.
Dengue Shock Syndrome and Haemodynamic Assessment
Dengue shock syndrome (DSS) results from massive plasma leakage caused by increased vascular permeability, a hallmark of dengue pathophysiology. Unlike septic shock, which involves vasodilation, DSS is a distributive shock characterised by leakage of plasma proteins and fluid into the extravascular compartment. This creates haemoconcentration (rising haematocrit) even as intravascular volume falls.
The hallmark haemodynamic finding in early DSS is a narrowing of the pulse pressure to below 20 mmHg, which occurs as diastolic blood pressure rises (compensatory peripheral vasoconstriction) while systolic blood pressure falls. Blood pressure may remain within the normal range until decompensation occurs, making pulse pressure a more sensitive early indicator than systolic blood pressure alone. In children, normal blood pressure values vary with age, and age-appropriate reference ranges must be applied.
A pulse pressure below 20 mmHg indicates compensated shock even when blood pressure appears within normal limits. In clinical practice, calculate pulse pressure by subtracting diastolic from systolic blood pressure. Early identification of compensated shock allows fluid resuscitation before the patient decompensates to profound hypotension.
Haematocrit and Platelet Count in Dengue Assessment
Serial monitoring of haematocrit (PCV) and platelet count is essential in managing dengue patients. A rising haematocrit of 20% or more above the patient’s baseline (or above age- and sex-appropriate normal values) is a reliable indicator of plasma leakage and signals the onset of the critical phase. It is important to use the trend – a single haematocrit value is less informative than the rate of change.
Thrombocytopenia (low platelet count) is nearly universal in dengue and worsens during the febrile and critical phases. Platelet counts below 100,000 per microlitre are common; below 20,000 increases the risk of spontaneous bleeding. However, it is critical to understand that platelet count alone does not reliably predict bleeding risk in dengue. Significant haemorrhage is uncommon even with profound thrombocytopenia in the absence of other coagulopathy or vascular injury. Prophylactic platelet transfusion is not routinely recommended in the absence of active significant bleeding.
The Tourniquet Test in Dengue Diagnosis
The tourniquet test (Rumpel-Leede test) is a bedside capillary fragility test that supports the diagnosis of dengue when positive. It is performed by inflating a blood pressure cuff to a point midway between the systolic and diastolic blood pressure and maintaining it for five minutes, then counting the number of petechiae (pinpoint haemorrhages) in a 2.5 cm x 2.5 cm (one square inch) area on the forearm below the cuff.
A result of 10 or more petechiae per square inch is considered positive. The sensitivity of the tourniquet test for dengue varies widely (40 to 90%) across studies, but its specificity is reasonable when interpreted in the correct clinical context. A positive tourniquet test in a febrile patient with headache, retro-orbital pain, myalgia, and arthralgia in an area where dengue is endemic is a clinically useful finding that increases diagnostic probability and supports the decision to perform dengue serology or NS1 antigen testing.
Clinical Phases of Dengue Fever
Dengue illness follows three distinct clinical phases that every clinician managing dengue should understand. These phases guide expectations for disease progression and the timing of investigations and interventions.
The febrile phase typically lasts two to seven days. Patients present with sudden onset high fever (often 39 to 40 degrees Celsius), severe headache, retro-orbital pain, myalgia, arthralgia, and sometimes a maculopapular rash. Facial flushing, nausea, and vomiting are common. The full blood count may show early leukopenia (low white cell count) and a normal or mildly reduced platelet count. NS1 antigen testing has the highest sensitivity during this phase (typically days one to five).
The critical phase occurs around defervescence (fever breaking), typically between days three and seven. This is the period of plasma leakage and highest risk. Haematocrit rises, platelets fall rapidly, and warning signs may emerge. Most patients who will develop severe dengue do so during this phase. Intensive monitoring is required even for patients who appear to be improving clinically as their temperature normalises.
The recovery phase begins when plasma leakage stops and fluid reabsorption starts, typically 48 to 72 hours after the start of the critical phase. Appetite returns, haematocrit normalises or may fall slightly as reabsorbed fluid dilutes the blood, platelets begin to recover, and the patient develops a characteristic convalescent rash. During recovery, fluid overload is a risk – particularly in patients who received large-volume intravenous fluids during the critical phase.
During recovery, reabsorption of leaked plasma back into the intravascular compartment can cause fluid overload, pulmonary oedema, and haemodynamic strain. Intravenous fluids should be reduced or stopped early in recovery. Patients should be monitored for signs of fluid overload: increasing respiratory distress, decreasing heart rate, or worsening blood pressure after initial improvement.
Dengue in Special Populations
Certain patient groups face higher risk of severe dengue and require heightened clinical vigilance. These include infants, elderly patients, pregnant women, and individuals with comorbid conditions such as obesity, diabetes mellitus, hypertension, chronic kidney disease, or haematological disorders.
In infants, dengue can be particularly severe. The normal physiological polycythaemia of infancy makes haematocrit interpretation more complex, and clinical dehydration may be difficult to distinguish from plasma leakage. Infants have less physiological reserve and may deteriorate more rapidly than older children or adults.
Pregnant women with dengue face risks of maternal haemorrhage, premature labour, and vertical transmission to the foetus. The physiological anaemia of pregnancy complicates haematocrit interpretation, and fluid management must account for the increased circulating volume of pregnancy.
Patients with concurrent conditions such as peptic ulcer disease, haemolytic conditions, or those on anticoagulant therapy face substantially elevated bleeding risk in dengue. Non-steroidal anti-inflammatory drugs (NSAIDs) and aspirin must be avoided in dengue due to their antiplatelet effects and risk of gastric bleeding.
Dengue Serology and Diagnostics
Laboratory diagnosis of dengue is confirmed by one or more of the following: isolation of the dengue virus from serum; detection of dengue viral RNA by reverse transcription polymerase chain reaction (RT-PCR); detection of dengue NS1 antigen by rapid test or enzyme-linked immunosorbent assay (ELISA); or detection of dengue-specific IgM or IgG antibodies.
The timing of infection significantly affects which test is most appropriate. During days one to five of illness (the early febrile phase), NS1 antigen testing and RT-PCR have the highest sensitivity. After day five, as the immune response matures, dengue IgM serology becomes positive. In secondary dengue infections (where a person has been previously infected with a different dengue serotype), IgG may rise more rapidly and become the predominant antibody. Negative dengue serology in the first five days does not exclude dengue – repeat testing or NS1 testing should be performed.
A 28-year-old woman presents on day four of fever (39.2 degrees Celsius), with severe myalgia, retro-orbital pain, and a maculopapular rash. She has mild nausea but no vomiting. Her tourniquet test shows 12 petechiae per square inch. Full blood count shows WBC 2.8 x 10^9/L, platelets 65,000, haematocrit 38%. She has no warning signs: no abdominal pain, no mucosal bleeding, no lethargy, no fluid accumulation, and liver is not enlarged. No severe dengue features.
Classification: Dengue without warning signs. She requires dengue serology/NS1 testing, oral hydration, paracetamol for fever and pain (not NSAIDs), and clear return instructions for warning signs – particularly as she is approaching the critical defervescence period. Daily follow-up review is appropriate.
Fluid Management in Dengue
Fluid management is the cornerstone of dengue treatment. There are no antiviral agents with proven efficacy against dengue, and platelet transfusion is reserved for patients with significant active bleeding. The primary therapeutic intervention is careful fluid replacement to compensate for plasma leakage while avoiding fluid overload.
For patients with dengue without warning signs and adequate oral intake, oral rehydration at home with clear instructions to return if warning signs develop is appropriate. For patients with warning signs or who cannot tolerate oral fluids, intravenous fluid therapy using isotonic crystalloid solutions (normal saline or Ringer’s lactate) is the standard approach. Fluid rates are guided by clinical response – vital signs, haematocrit trends, urine output (target 0.5 to 1 ml/kg per hour), and capillary refill time.
In dengue shock syndrome, fluid resuscitation begins with an intravenous isotonic crystalloid bolus of 10 ml/kg over 15 to 30 minutes with immediate clinical reassessment. This approach differs from septic shock management, where larger initial boluses are commonly used. Excessive fluid resuscitation in dengue can precipitate pulmonary oedema during the recovery phase when leaked plasma is reabsorbed.
Global Epidemiology and Transmission
Dengue is endemic in more than 100 countries across tropical and subtropical regions of the world, with highest burden in Southeast Asia, the Western Pacific, the Americas (particularly the Caribbean and South America), and parts of Africa and South Asia. The global incidence of dengue has increased dramatically over the past five decades, driven by rapid urbanisation, population growth, inadequate vector control, and climate change expanding the geographical range of Aedes mosquitoes.
The four dengue serotypes co-circulate in endemic areas, and immunity to one serotype does not provide protection against the others. Secondary infection with a different serotype is associated with a higher risk of severe dengue due to antibody-dependent enhancement (ADE), in which pre-existing cross-reactive antibodies from the first infection facilitate viral entry into monocytes and macrophages during the second infection, amplifying viral replication. This mechanism partly explains why severe dengue is more common in individuals experiencing their second dengue infection.
Individuals experiencing their second dengue infection with a different serotype face an elevated risk of severe dengue, partly due to antibody-dependent enhancement. In endemic regions, severe dengue disproportionately affects children aged 5 to 15 years who are experiencing secondary infections. This risk profile differs in populations newly exposed to dengue, where primary infection in adults can also result in severe disease.
Dengue Prevention and Vector Control
Prevention of dengue relies primarily on control of the Aedes aegypti mosquito, which breeds in small accumulations of clean standing water around human habitation – flower pots, discarded tyres, water storage containers, and drains. Vector control measures include source reduction (eliminating breeding sites), larviciding, and adult mosquito control using insecticides. Personal protective measures include the use of insect repellents containing DEET, picaridin, or IR3535, wearing long-sleeved clothing, and using mosquito nets and window screens.
A dengue vaccine (Dengvaxia, CYD-TDV, manufactured by Sanofi Pasteur) is licensed in several countries for use in individuals aged nine years and above who have had a confirmed prior dengue infection. It is not recommended for dengue-naive individuals, as it may increase the risk of severe dengue upon subsequent natural infection in that group. A second-generation dengue vaccine (TAK-003, Qdenga, manufactured by Takeda) has received regulatory approval in the European Union and several other countries and demonstrates efficacy against all four serotypes regardless of serostatus, though post-licensure safety monitoring is ongoing.
Differential Diagnosis of Dengue
Dengue must be distinguished from other febrile illnesses that share clinical features. Important differential diagnoses include malaria (which can cause similar fever patterns, thrombocytopenia, and severe disease), chikungunya (which is also transmitted by Aedes mosquitoes and causes fever and severe arthralgia), Zika virus infection (generally milder, with conjunctivitis and rash as distinctive features), leptospirosis, typhoid fever, and other viral haemorrhagic fevers.
In non-endemic regions or in returned travellers, the clinical presentation of dengue may be unfamiliar to clinicians, and a travel history is essential. Any febrile patient who has returned from a dengue-endemic region within 14 days should have dengue included in the differential diagnosis, and appropriate diagnostic testing should be performed promptly.
Monitoring Parameters During Hospital Admission
For patients admitted with dengue with warning signs or severe dengue, a structured monitoring protocol is essential. Vital signs (blood pressure, heart rate, respiratory rate, temperature) should be monitored every one to four hours depending on clinical severity. Haematocrit and platelet count should be checked every four to six hours during the critical phase. Urine output should be measured and charted – a minimum output of 0.5 ml/kg per hour indicates adequate perfusion.
The decision to discharge a patient should be based on meeting all of the following criteria: no fever for at least 48 hours without the use of antipyretics; improvement in clinical status with good appetite; adequate urine output; stable or rising platelet count above 50,000; stable haematocrit without ongoing intravenous fluid support; and at least 48 hours elapsed since defervescence.
A 35-year-old male presents on day five of illness. Fever has just broken (current temperature 37.1 degrees Celsius). He complains of severe abdominal pain and has vomited four times in the past six hours. On examination, the liver is palpable 3 cm below the right costal margin. Haematocrit is 52% (his known baseline is 42%, representing a 24% rise). Platelet count is 35,000. No active bleeding is observed.
Classification: Dengue with Warning Signs (abdominal pain, persistent vomiting, liver enlargement, and significant haematocrit rise with rapid platelet drop). This patient requires hospital admission, intravenous fluid therapy, close monitoring of vitals and haematocrit, and assessment for progression to severe dengue. He should not be discharged until all discharge criteria are met.
Medications to Avoid in Dengue
Several commonly used medications are contraindicated or carry significant risk in dengue and must be avoided. Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen, and diclofenac inhibit platelet function and increase the risk of gastric bleeding, which can be catastrophic in a patient with dengue-associated thrombocytopenia. Aspirin shares these antiplatelet properties and should be similarly avoided.
Intramuscular injections should be avoided in dengue patients with thrombocytopenia due to the risk of intramuscular haematoma. Corticosteroids and intravenous immunoglobulin have been studied in dengue but are not recommended in routine management based on current evidence. Paracetamol (acetaminophen) at appropriate doses is the analgesic and antipyretic of choice in dengue, as it does not affect platelet function. High doses of paracetamol should also be avoided due to hepatotoxicity risk, particularly if dengue-related hepatitis is present.
Paediatric Dengue Considerations
Dengue in children shares the same fundamental pathophysiology as in adults but has several important clinical differences. Children may be unable to verbalise symptoms accurately, and non-specific signs such as refusal to feed, irritability, or lethargy may be the presenting features. Vital sign interpretation must use age-appropriate reference ranges – tachycardia and blood pressure norms differ substantially between infants, toddlers, school-age children, and adolescents.
Haematocrit reference ranges are also age-dependent, and the 20% rise criterion must be applied relative to the child’s appropriate baseline. Fluid calculations are based on body weight. The WHO recommends weight-based fluid resuscitation protocols specifically calibrated for paediatric patients. Clinicians should use paediatric dengue management protocols, particularly for young infants in whom dengue can be especially life-threatening.
The following features indicate a medical emergency requiring immediate hospital attendance: severe abdominal pain that is constant or worsening; repeated vomiting (three or more times in the past hour); bleeding from the nose, gums, or in vomit or stool; drowsiness, confusion, or difficulty waking; pale, cold, or clammy skin; rapid breathing; or fainting. These are not symptoms to manage at home while waiting for a scheduled clinic appointment.
Role of This Calculator in Clinical Practice
This dengue severity calculator is designed as a structured clinical decision support tool that guides healthcare workers through the systematic assessment of dengue severity according to the WHO 2009 classification. By prompting evaluation of each diagnostic criterion – including the presence of warning signs and severe dengue features – it reduces the risk of overlooking critical findings in a busy clinical environment.
The calculator is intended to support, not replace, clinical judgement. Dengue is a dynamic illness that evolves over days, and a single assessment reflects the clinical state at one point in time. Repeat assessment is essential as the illness progresses, particularly around defervescence. All clinical findings must be interpreted in the context of the individual patient, local epidemiology, available laboratory results, and the clinical experience of the treating team.
Frequently Asked Questions
Conclusion
Dengue fever remains a significant global public health challenge, with its clinical management depending critically on accurate and timely severity assessment. The WHO 2009 classification system provides a clear, clinically actionable framework – categorising patients as dengue without warning signs, dengue with warning signs, or severe dengue – that directly guides treatment decisions from home management to emergency hospital care.
The key principles of dengue management are recognising the warning signs that predict progression to severe disease, understanding the pathophysiology of plasma leakage and its haemodynamic consequences, providing appropriate fluid therapy guided by clinical response and haematocrit trends, and avoiding medications that increase bleeding risk. This dengue severity calculator supports clinicians in applying these principles systematically, reducing the risk of missed or delayed diagnosis in a time-critical illness.
Dengue is a preventable disease, and personal protective measures against Aedes mosquito exposure remain the primary prevention strategy in the absence of universal vaccine availability. For any patient with suspected dengue, early clinical assessment, appropriate laboratory investigation, and clear education about warning signs – with immediate access to emergency care if they develop – are the cornerstones of safe management.
This calculator is provided for informational and educational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare professional before making any medical decisions. The results from this calculator should be used as a reference guide only and not as the sole basis for clinical decisions. Dengue is a dynamic illness – severity can change rapidly, and continuous clinical monitoring by trained healthcare professionals is essential.