Symptoms of yellow fever virus

Early illness may cause sudden fever, chills, headache, backache, muscle aches, nausea, vomiting, and marked tiredness. Some people improve after this early phase, while others develop a more serious illness. Warning features include yellowing of the eyes or skin, dark urine, abdominal pain, bleeding, confusion, reduced urine, or extreme sleepiness. Symptoms can overlap with other infections, so appearance alone cannot confirm the cause.

Seek medical advice urgently if you develop symptoms after living in or travelling through an area where yellow fever occurs, especially if you were exposed to mosquitoes. Tell the clinician where you travelled, when you returned, whether you received vaccination, and which medicines you take. Rest and drink fluids if you can, but do not delay assessment because symptoms temporarily improve.

Go to urgent or emergency care for confusion, difficulty staying awake, trouble breathing, repeated vomiting, severe abdominal pain, bleeding, yellow skin or eyes, very little urine, or rapidly worsening fever. Yellow fever can affect the liver, kidneys, and blood-clotting system, so serious symptoms require hospital assessment. Avoid donating blood and follow infection-control advice while being assessed.

Ask whether your travel history makes yellow fever possible, which tests or monitoring may be needed, and how to manage fluids and fever safely. Ask what symptoms should bring you back immediately and whether household or travel contacts need prevention advice.