Symptoms

During the first three to six days after you've developed yellow fever — the incubation period — you won't experience any signs or symptoms. After this, the infection enters an acute phase and then, in some cases, a toxic phase that can be life-threatening.

Acute phase

Once the infection enters the acute phase, you may experience signs and symptoms including:

• Fever
• Headache
• Muscle aches, particularly in your back and knees
• Sensitivity to light
• Nausea, vomiting or both
• Loss of appetite
• Dizziness
• Red eyes, face or tongue

These signs and symptoms usually improve and are gone within several days.

Toxic phase

Although signs and symptoms may disappear for a day or two following the acute phase, some people with acute yellow fever then enter a toxic phase. During the toxic phase, acute signs and symptoms return and more-severe and life-threatening ones also appear. These can include:

• Yellowing of your skin and the whites of your eyes (jaundice)
• Abdominal pain and vomiting, sometimes of blood
• Decreased urination
• Bleeding from your nose, mouth and eyes
• Slow heart rate
• Liver and kidney failure
• Brain dysfunction, including delirium, seizures and coma

The toxic phase of yellow fever can be fatal.

When to see a doctor

Before travel

• Four weeks or more before your trip, make an appointment to see your doctor if you're traveling to an area in which yellow fever is known to occur so that you discuss whether you need the yellow fever vaccine.
• If you have less than four weeks to prepare, call your doctor anyway. Ideally, you'll be able to be vaccinated at least three to four weeks before traveling to an area where yellow fever occurs to give the vaccine time to work. Your doctor will help you determine whether you need vaccinations and can provide general guidance on protecting your health while abroad.

After travel

• Seek emergency medical care if you've recently traveled to a region where yellow fever is known to occur and you develop signs or symptoms of the toxic phase of the disease.
• Call your doctor if you develop mild symptoms, after traveling to a region where yellow fever occurs.