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Dengue is a viral infection spread by Aedes aegypti or Aedes albopictus mosquitoes. It typically causes a high fever, severe headache, pain behind the eyes, muscle and joint aches, rash, and vomiting. Most people recover in about a week. However, in a small number of cases, the illness becomes life-threatening. This most severe form is known as dengue shock syndrome or severe dengue. In dengue shock syndrome, blood plasma leaks from blood vessels into surrounding tissues, causing a dangerous drop in blood pressure (shock) and sometimes internal bleeding (World Health Organization, 2024).
Severe Dengue usually develops after the initial fever phase. As the fever subsides (typically 3–7 days after symptoms begin), the body may enter a critical phase. During this stage, the immune system’s response can make blood vessels unusually permeable, allowing plasma to leak into surrounding tissues. This leakage reduces the amount of circulating blood, which may lead to low blood pressure, poor organ perfusion, and potentially shock.
Phases of Severe Dengue
Dengue infection generally follows three phases. First, there is a febrile phase of high fever (usually 3–7 days) with the typical symptoms of fever, headache, rash and aches. This often feels like a bad flu. After about 3–7 days, the fever goes down and you may feel better. For most people, this is the end of the illness.
However, around the time the fever falls, warning signs of severe dengue can appear. In this critical phase, the body may leak plasma from the blood vessels. The resulting loss of fluid can cause blood pressure to fall dangerously low (shock). When shock develops, organs can start to fail. Early detection is crucial, since shock can occur quickly once fluid leakage overwhelms the body’s compensatory mechanisms (Centers for Disease Control and Prevention, 2024).
Next is the Recovery Phase (2–3 days after the critical phase, if the patient stabilises). Fluid that leaked out begins to be reabsorbed into the bloodstream. Appetite improves, urine output increases, and patients generally feel stronger.
Warning Signs and Symptoms
Anyone with dengue should be vigilant for warning signs that severe dengue may be developing.
- Severe abdominal pain or tenderness.
- Repeated vomiting – especially vomiting three or more times in 24 hours
- Persistent diarrhoea – more than three times a day
- Lethargy or restlessness – feeling unusually tired, weak, or unable to sit still
- Mucosal bleed
Why Early Intervention is Crucial
Early intervention in severe dengue is critical because the disease can progress rapidly once the patient enters the critical phase. Prompt intervention allows for close monitoring of hematocrit, platelet count, urine output, and vital signs, allowing for early and careful fluid replacement. Additionally, early detection of warning signs provides an opportunity to anticipate and manage complications such as severe bleeding or organ impairment.
Book an Appointment at Gleneagles Hospitals
Recognising the warning signs of Dengue Fever early can save lives. If you or someone you know recently has symptoms such as abdominal pain, persistent vomiting, bleeding (from gums, nose, or in stool/vomit), sudden unexplained fatigue, or difficulty breathing during or after a recent febrile illness, seek immediate medical attention immediately.
If you have questions about dengue or need further medical advice, contact us to book an appointment at your nearest Gleneagles Hospitals. For dengue-related assessments or other health concerns, please reach out to the health screening centre at your local Gleneagles Hospitals. You may also book an appointment by downloading the MyHealth360 application from the Google Play Store or Apple App Store.
