Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes YF Vax (Yellow-fever-vaccine). If you are concerned about side effects, discuss the risks and benefits of YF Vax (Yellow-fever-vaccine) with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• fever
• headache
• nausea
• pain, redness, or swelling at the injection site

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• muscle aches
• signs of liver problems (e.g., nausea, vomiting, Diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• confusion
• high fever with headache
• seizures
• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking YF Vax (Yellow-fever-vaccine).

When reconstituted with saline provided with the vaccine, each 0.5 mL dose of slightly pink-brown suspension contains at least 4.74 log10 plaque-forming units of yellow fever virus strain 17D-204. Nonmedicinal ingredients: sorbitol, gelatin, and sodium chloride injection USP.

Do not take this medication if you:

• are allergic to yellow fever virus or any ingredients of the medication
• are allergic to eggs, chicken protein, or latex
• are taking medications that reduce the effectiveness the immune system
• have any conditions that affect the immune system (e.g., HIV/AIDS, Leukemia lymphoma)
• have had your thymus gland removed, or have a history of problems with the thymus such as thymoma or Myasthenia Gravis

Do not give YF Vax (Yellow-fever-vaccine) to infants under 9 months of age.

There may be an interaction between yellow fever vaccine and any of the following:

• Acetaminophen
• Belimumab
• dimethyl fumarate
• Fingolimod
• immunosuppressants (medications used to treat cancer or autoimmune disease or prevent organ rejection)
• Azathioprine
• corticosteroids (e.g., budesonide, Dexamethasone, Hydrocortisone, fluticasone, Prednisone)
• Cyclosporine
• Hydroxyurea
• Infliximab
• medications to treat cancer (e.g., Carboplatin, Cyclophosphamide, Doxorubicin, Ifosfamide, Vincristine)
• mycophenolate
• Rituximab
• Tacrolimus
• Leflunomide
• tuberculin tests
• Warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with YF Vax (Yellow-fever-vaccine). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use YF Vax (Yellow-fever-vaccine).

Allergic reactions: As with any vaccine, allergic reactions are possible with the yellow fever vaccine. Your doctor may want you to remain in the clinic or office for a period of time after receiving the vaccine, to ensure that you do not develop an allergic reaction.

Immune system: As with any vaccine, this vaccine may not be as effective for people with a weakened immune system (e.g., people with AIDS or cancer, people taking antirejection medications after an organ transplant, people receiving chemotherapy, people taking any medication that suppresses the immune system). If you or your child has a weakened immune system, the doctor may decide to postpone the vaccine until the immune system recovers.

Infection or fever: This vaccine should not be given to anyone who has an active infection or an illness associated with fever, unless the doctor decides that the benefits outweigh the risks.

Vaccine protection: As with any vaccine, this vaccine may not protect 100% of people who receive it and may not prevent infection in those people already infected with the virus.

Pregnancy: YF Vax (Yellow-fever-vaccine) should not be used during pregnancy unless the benefits outweigh the risks.

Breast-feeding: It is not known if yellow fever vaccine passes into breast milk. If you are a breast-feeding mother and are taking YF Vax (Yellow-fever-vaccine), it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using YF Vax (Yellow-fever-vaccine) have not been established for children less than 9 months old. Infants less than 9 months old are at an increased risk of developing encephalitis as a result of receiving this vaccine.

Seniors: People over the age of 60 may be more at risk of developing complications from this vaccine.