Side effects of yellow fever

Yellow fever is a mosquito-borne viral infection. Early illness may feel like a flu-like infection, with sudden fever, headache, back or muscle aches, chills, nausea, vomiting and marked tiredness. Some people improve after the early phase, while others develop a more serious illness affecting the liver, blood clotting and other organs. Yellowing of the skin or whites of the eyes, dark urine, unusual bleeding, confusion or severe abdominal pain are concerning changes rather than ordinary vaccine reactions.

If you have fever or other symptoms after travel in, or exposure to, an area where yellow fever occurs, arrange prompt medical assessment and mention your travel dates, mosquito bites and vaccination history. Rest, drink fluids if you can keep them down, and reduce mosquito exposure so mosquitoes are less likely to acquire and spread the virus. Do not self-treat with medicines that may increase bleeding risk without clinical advice. A clinician can decide which tests and supportive care are appropriate.

Seek emergency care for difficulty breathing, fainting, confusion, seizures, severe weakness, persistent vomiting, yellow skin or eyes, very dark urine, bleeding, severe abdominal pain or inability to drink. Symptoms can worsen quickly, especially when fever is followed by a brief improvement and then returns with new warning signs. Tell the service about recent travel and possible mosquito exposure.

Ask whether your symptoms fit yellow fever or another travel-related infection, whether testing is needed, how to manage fever safely, and which warning signs should prompt immediate review. Ask how to protect household members from mosquito bites while you are unwell.