Dengue Warning Signs: When the Fever Drops and Danger Begins

Three days of high fever, a headache behind the eyes, body pain that makes you feel a decade older. Then, on day four, the fever goes. Most people relax at this point. With dengue, that is exactly the moment to pay closer attention.

Most dengue infections are mild and get better with rest and fluids. A small share turn severe, and the turn usually comes around the time the fever settles. Knowing the pattern, and the handful of signs that mean you need a hospital today, is the most useful thing you can carry into the monsoon season.

How dengue usually runs: three phases

Dengue is a viral infection spread by the bite of an infected Aedes mosquito. There are four types of dengue virus, which is why a person can get dengue more than once. A second infection with a different type carries a higher risk of severe disease, so a past episode is no reason to take a new one lightly.

Doctors describe the illness in three phases:

1. Febrile phase. Sudden high fever lasting roughly two to seven days, with headache, pain behind the eyes, muscle and joint pain, nausea and sometimes a rash. This is the miserable part, but usually not the dangerous part.
2. Critical phase. Around the time the fever comes down, often somewhere between day three and day seven, some people develop leaky blood vessels. Fluid seeps out of the blood into the tissues, the blood thickens and blood pressure can fall. This window typically lasts a day or two.
3. Recovery phase. The leaked fluid is reabsorbed, appetite returns and energy slowly comes back. Tiredness can linger for a week or more.

The trap is obvious once you see it. The fever drops, the family thinks the worst is over, and the patient is quietly getting worse. So for the first two days after the fever breaks, keep watching.

Warning signs that mean hospital now

The WHO and India's Ministry of Health list a set of warning signs that suggest dengue may be turning severe. In plain words, go to a hospital the same day, and call 108 or 112 if the person is very unwell, if you notice any of these:

• Severe or constant pain in the belly
• Vomiting again and again, or being unable to keep fluids down
• Bleeding from the gums or nose, blood in vomit, or black, tarry stools
• Unusual drowsiness, confusion, restlessness or irritability
• Cold, clammy hands and feet, or feeling faint on standing
• Fast or difficult breathing
• Passing very little urine, for example nothing in four to six hours in an adult

Children, pregnant women, older adults and people with diabetes, heart, kidney or liver disease deserve a lower threshold. If you are unsure, get checked. A hospital sending you home with reassurance is a far better outcome than waiting too long.

Paracetamol yes, ibuprofen and aspirin no

For fever and pain in suspected dengue, the usual choice is paracetamol, taken at the dose and interval your doctor or the label gives. More is not better. Taking extra paracetamol to chase a stubborn fever can harm the liver, and dengue itself can stress the liver. Sponging with lukewarm water helps bring the temperature down between doses.

Avoid ibuprofen, aspirin, diclofenac and similar painkillers (the group doctors call NSAIDs) unless a doctor who knows you have dengue says otherwise. They affect how platelets work and can irritate the stomach lining, which raises the risk of bleeding at the very time the body is least able to cope with it. Many combination cold and pain tablets contain one of these, so read the strip before you swallow anything.

There is no antiviral medicine that cures dengue. Treatment is about supporting the body through the illness, mainly with fluids and careful monitoring.

Fluids: the simplest treatment that actually works

Because the danger in dengue is fluid leaking out of the blood vessels, staying well hydrated is the main thing you can do at home. Oral rehydration solution (ORS), water, coconut water, rice kanji, dal water, soups and fresh juices all count. Small, frequent sips are easier than large glasses if the person feels sick.

A simple way to keep track is to watch urine. Regular passing of pale urine is reassuring. Dark urine, or long gaps without passing any, means the person is not getting enough fluid, or that something more serious is happening, and needs a doctor's review.

Do not force fluids into someone who is vomiting repeatedly or is drowsy. That is a warning sign in itself and belongs in a hospital, where fluids can be given carefully through a drip.

Platelet counts, papaya leaves and other myths

Platelet counts get enormous attention during dengue season, and the falling number on each blood report can cause real panic. A few honest points:

• Platelets often fall in dengue, usually around the critical phase, and then recover on their own as the illness passes.
• The count alone does not tell the whole story. Doctors look at the platelet count together with the haematocrit (how concentrated the blood is), blood pressure, urine output and warning signs. A rising haematocrit with a falling platelet count is more worrying than either number alone.
• Most people do not need a platelet transfusion. Doctors generally reserve it for significant bleeding or particular situations. Asking for one because the number looks low is not a good reason.

What about papaya leaf juice, goat milk, kiwi fruit and the rest? A few small studies have looked at papaya leaf extract and platelet counts, but the evidence is limited and it has not been shown to prevent severe dengue. Home remedies are not a substitute for fluids, monitoring and a doctor, and they are never a reason to delay going to hospital when a warning sign appears.

On testing: in the first few days of fever, doctors commonly order an NS1 antigen test, and an antibody test (IgM) becomes useful a few days later. A complete blood count, repeated as advised, tracks platelets and haematocrit.

Stopping mosquitoes at home

The Aedes mosquito breeds in small amounts of clean, still water, often inside or right next to the house, and it bites mainly during the daytime, especially early morning and late afternoon. That shapes what works.

• Empty, scrub and dry anything that holds water at least once a week: cooler trays, flower vase water, plant saucers, the drip tray under the fridge, buckets and pet bowls. Scrubbing matters because the eggs can stick to container walls and survive for a long time.
• Cover water storage such as overhead tanks, drums and sumps with tight lids.
• Clear the terrace and balcony of old tyres, coconut shells, broken pots and plastic that collect rainwater.
• Protect people with full-sleeved clothes, mosquito repellent on exposed skin, window screens, and nets for babies and anyone sleeping during the day.

Many municipalities and the national vector-borne disease programme under the Ministry of Health promote a weekly dry day for exactly this reason. One house that breeds mosquitoes can affect the whole lane, so it is worth mentioning to neighbours and your housing society too.

The one thing to remember

When someone with dengue says the fever has finally gone, keep watching for the next 48 hours. Keep them drinking, give only paracetamol for pain, check that they are passing urine, and go to hospital at the first warning sign rather than waiting for the next blood report.

This article is general information, not medical advice. If you think you or someone at home has dengue, please see a doctor, and call 108 or 112 in an emergency.