How does this medication work? What will it do for me?

Japanese encephalitis vaccine belongs to the class of medications called vaccines. It is used by people 18 years and older to prevent Japanese encephalitis. Japanese encephalitis is caused by a virus which is passed to humans who are bitten by an infected mosquito. This vaccine increases your defenses against the Japanese encephalitis virus by stimulating the production of your own antibodies, which will remain in your body until needed to fight off this virus if you are ever exposed.

The Japanese encephalitis vaccine is recommended for adults who are travelling to or living in areas where Japanese encephalitis exists. Vaccination is also recommended for laboratory workers who routinely handle specimens that contain or are believed to contain this virus.

Your doctor may have suggested this vaccine for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are receiving this vaccine, speak to your doctor.

What form(s) does this medication come in?

Each 0.5 mL of white, cloudy, sterile suspension contains 6 micrograms of inactivated Japanese encephalitis virus. Nonmedicinal ingredients: aluminum hydroxide hydrated, disodium hydrogen phosphate, potassium dihydrogen phosphate, sodium chloride, and water for injection

How should I use this medication?

The usual adult dose of Japanese encephalitis vaccine is 0.5 mL given as an injection intramuscularly (into the muscle). The first dose is given at the initial visit, with the second dose given 28 days later.

This vaccine is given by a health care professional in a doctor's office, hospital, or clinic.

It is very important that this vaccine be given on a regular schedule as prescribed by the doctor. If you miss an appointment to receive Japanese encephalitis vaccine, contact your doctor as soon as possible to reschedule your appointment.

It takes 7 days for immunity to develop after receiving the second dose of this vaccine, so it is important that the second dose be given at least 7 days before entering an area where you may come into contact with the virus that causes Japanese encephalitis.

This medication is stored in the refrigerator and should not be allowed to freeze.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to Japanese encephalitis vaccine or any ingredients of the medication
  • have developed an allergic reaction after the first dose of this vaccine
  • have an acute, severe infection
  • have a bleeding disorder

What side effects are possible with this medication?

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 this medication. If you are concerned about side effects, discuss the risks and benefits of this medication 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.

  • flu-like symptoms
  • general sense of being unwell
  • headache
  • muscle pain
  • nausea
  • pain at the site of injection
  • tiredness
  • vomiting

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:

  • itchiness
  • migraine
  • muscle stiffness
  • skin rash

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

  • 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 this medication.

Are there any other precautions or warnings for this medication?

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 this medication.

Bleeding disorders: If you have a bleeding disorder or are taking medications that make you more likely to bleed (i.e., warfarin, acetylsalicylic acid [ASA]) tell the person giving you the injection. There is a risk of excessive bleeding where you get the injection if it is not done carefully.

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 have a weakened immune system, your doctor may decide to postpone the vaccine until your 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: This medication should not be used during pregnancy unless the benefits outweigh the risks.

Breast-feeding: It is not known if Japanese encephalitis vaccine passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

What other drugs could interact with this medication?

There may be an interaction between Japanese encephalitis vaccine and any of the following:

  • acetaminophen
  • belimumab
  • 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
  • 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 this medication. 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.