How effective is a blood test for dengue fever?

Early in dengue, a blood test may look for material from the virus; later, it may look for antibodies made by the immune system. A test taken very early can be negative even when dengue is developing, while antibodies can remain after a past infection. A full blood count may show falling platelets or changes in other blood cells, but those findings are not unique to dengue.

Your travel or mosquito exposure, fever pattern, rash, headache, muscle pain, bleeding symptoms and examination help the clinician interpret the result. Repeat testing may be considered when symptoms and the first result do not match.

Tell the clinician when the fever started, where you have travelled, whether mosquito exposure occurred and which medicines you have taken. Follow advice about fluids and rest. Avoid aspirin or ibuprofen unless a clinician specifically says they are suitable, because dengue can increase bleeding risk. Use paracetamol only as directed and arrange follow-up if fever persists or returns.

Seek urgent care for severe abdominal pain, repeated vomiting, bleeding from the gums or nose, blood in vomit or stools, extreme sleepiness, breathing difficulty, cold or clammy skin, or very little urine. Warning signs can appear as fever settles, so worsening symptoms need review even after a negative test.

Ask which dengue test is being used, whether the timing is suitable, if repeat testing or a full blood count is needed, and which pain medicines and fluids are safe for you.