Yellow fever vaccine is recommended for people who plan to live in or travel to areas where yellow fever is known to exist, or those who are otherwise at high risk of coming into contact with the virus.

This vaccine is used to help prevent yellow fever. The vaccine works by exposing you to a small dose of the virus, which causes the body to develop immunity to the disease. This vaccine will not treat an active infection that has already developed in the body.

You should receive the vaccine at least 10 days prior to your arrival in an area where you may be exposed to the virus.

This vaccine is also recommended for people who work in a research laboratory and may be exposed to yellow fever virus through needle-stick accidents or inhalation of viral droplets in the air.

Like any vaccine, the yellow fever vaccine may not provide protection from disease in every person.

You should not receive this vaccine if you have ever had a life-threatening allergic reaction to a yellow fever vaccine, or if you have:

• an allergy to eggs or chicken proteins;
• cancer, leukemia, or lymphoma;
• a weak immune system caused by disease (such as cancer, HIV, or AIDS), or by taking certain medicines such as steroids;
• a disorder such as myasthenia gravis;
• a disease or tumor of the thymus gland, or if your thymus gland has been surgically removed; or
• if you have received a transplant.

Children younger than 9 months should not receive yellow fever vaccine.

If you have a high risk of exposure to yellow fever, you may need to receive the vaccine even if you have an allergy to eggs or chicken products. Your doctor can give you the vaccine in several small doses to avoid an allergic reaction.

In special cases, a doctor or health official may determine that an adult 60 years and older should receive a yellow fever vaccine.

Tell your doctor if you have ever had:

• a seizure;
• a neurologic disorder or disease affecting the brain (or if this was a reaction to a previous vaccine);
• a bleeding or blood clotting disorder such as hemophilia; or
• Guillain Barré syndrome.

You can still receive a vaccine if you have a minor cold. In the case of a more severe illness with a fever or any type of infection, wait until you get better before receiving this vaccine.

Vaccines may be harmful to an unborn baby and generally should not be given to a pregnant woman. However, not vaccinating the mother could be more harmful to the baby if the mother becomes infected with a disease that this vaccine could prevent. Your doctor will decide whether you should receive this vaccine, especially if you have a high risk of infection with yellow fever.

Ask a doctor if it is safe to breastfeed after receiving this vaccine. Do not breastfeed if the child is less than 9 months old.

Use YF-Vax (Subcutaneous) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction: hives; wheezing, chest tightness, difficult breathing, swelling of your face, lips, tongue, or throat.

You should not receive a booster vaccine if you had a life-threatening allergic reaction after the first vaccine. Keep track of all side effects that occur within 30 days after you receive this vaccine. If you ever need a booster dose, you will need to tell your doctor if the previous shot caused any side effects.

Seek medical attention right away if you have any of these symptoms similar to yellow fever that may occur within 10 days after vaccination:

• fever, headache, confusion, extreme tiredness;
• muscle pain or weakness;
• a light-headed feeling, like you might pass out;
• easy bruising, unusual bleeding;
• little or no urination; or
• vomiting, loss of appetite, jaundice (yellowing of the skin or eyes).

Becoming infected with yellow fever is much more dangerous to your health than receiving this vaccine. However, like any medicine, this vaccine can cause side effects but the risk of serious side effects is extremely low.

Call your doctor at once if you have any of these rare but serious side effects within 10 days after you receive the vaccine:

• high fever, vomiting, increased sensitivity to light;
• extreme tiredness, neck stiffness, seizure;
• problems with walking, breathing, speech, swallowing, vision, or eye movement;
• weakness or prickly feeling in your fingers or toes;
• severe pain (especially at night); or
• loss of bladder or bowel control.

Serious side effects may be more likely in older adults.

Common side effects may include:

• fever;
• vomiting, nausea;
• headache;
• joint or muscle pain;
• tiredness or weakness; or
• pain, discomfort, redness, swelling, or a hard lump (induration) where the infection was given.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report vaccine side effects to the US Department of Health and Human Services at 1-800-822-7967.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.