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

This medication belongs to a group of medications known as vaccines. It is used to prevent influenza (the flu). Influenza is a common viral illness caused by 2 types of virus: influenza A and influenza B.

Each year, different strains (new, slightly different versions of the virus) appear. Scientists predict which strains will be most likely for the coming year, and then these strains are used to make up the year's influenza vaccine. Each year's influenza vaccine contains 3 to 4 virus strains that are likely to circulate in Canada in the coming winter. The vaccine only provides protection against the strains of flu virus used to prepare the vaccine.

It usually takes 2 to 3 weeks for the protection against these viruses to be effective, and the protection lasts for 6 to 12 months. Annual vaccination is necessary to make sure you are covered for the new virus strains that are expected each year.

The vaccine increases a person's defenses against the influenza virus. It works by introducing very small amounts of viral components (parts) into the body. These components are enough to stimulate the production of antibodies (cells designed to attack that particular virus), which will remain in the body ready to attack that same virus in the future. The vaccine is used to prevent influenza for people over 6 months of age who want to reduce their chances of getting the flu.

The National Advisory Committee on Immunization (NACI) recommends annual vaccination for:

  • any healthy person wanting protection from influenza
  • children aged 6 months to 18 years who are being treated with acetylsalicylic acid (ASA) for long periods of time
  • health care workers
  • healthy children aged 6 to 59 months
  • healthy pregnant women
  • household contacts (including children) of people at high risk who cannot be vaccinated or who may not respond to vaccination
  • people at high risk of complications of influenza that are travelling to areas where influenza is likely circulating
  • people over 65 years of age
  • people who have HIV
  • people with certain chronic health conditions, such as asthma, heart disease, diabetes, cancer, cystic fibrosis, anemia, or kidney disease
  • residents of nursing homes or chronic care facilities
  • people who provide regular care to children ages 0 to 23 months
  • people who provide essential community services
  • people who provide services within relatively closed settings to persons at high risk (e.g., crew on a ship)
  • people in direct contact with poultry infected with avian influenza, during culling operations

Your doctor may have suggested this vaccine for conditions other than the ones 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 dose of whitish, slightly opalescent suspension liquid contains 3 strains of influenza virus. Nonmedicinal ingredients: phosphate buffered saline (composed of: sodium chloride, potassium chloride, sodium phosphate dibasic heptahydrate, potassium phosphate monobasic, and water for injection), thimerosal (as a preservative), and small amounts of egg proteins, formaldehyde, sodium deoxycholate, and sucrose.

How should I use this medication?

The influenza vaccine is given once a year, usually in October or November, as an injection into a muscle (usually on the upper arm). It is given by a health care professional.

It is important this medication be given exactly as recommended by your doctor. If you miss an appointment to receive the influenza vaccine, contact your doctor as soon as possible to reschedule your appointment.

This medication is stored in the fridge and should be kept out of the reach of children. It should be protected from light and not 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?

The influenza vaccine should not be used by anyone who:

  • is allergic to any of the ingredients of this medication or any trace products found in this medication
  • has an active neurological disorder
  • has an acute illness (except for minor illnesses)

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.

  • aches or pains in muscles
  • fatigue
  • fever
  • general feeling of discomfort or illness
  • headache
  • tenderness, redness, or hard lump at place of injection

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

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

  • rash
  • nerve pain, numbness, or tingling

Seek immediate medical attention if any of the following occur:

  • symptoms of a severe allergic reaction (e.g., swollen face or throat, hives, or difficulty breathing)

Be sure to mention any side effect to your doctor, as it may mean that you are allergic to the vaccine. If so, it would not be safe for you to have more doses of the same type of vaccine.

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.

Allergic reactions: Rarely, this vaccine may cause severe allergic reactions. This is why your doctor may ask you to stay in the office for about 30 minutes after having the vaccine so that you can get medical care if you experience an allergic reaction. If you notice signs of a severe allergic reaction (hives; trouble breathing or swallowing; or swelling of the lips, face, throat, or tongue), get medical attention immediately.

Allergy to eggs: People who have an allergy to eggs that causes anaphylaxis (hives, swelling of the mouth and throat, difficulty breathing) should discuss with their doctor the risks and benefits of receiving this vaccine and whether any special monitoring is needed.

Bleeding: If you have a bleeding disorder or if you take anticoagulants (blood thinners), talk to your doctor about how this vaccine may affect your medical condition and whether any special monitoring is needed.

Guillain-Barre Syndrome (GBS): Guillain-Barre Syndrome, a neurological disorder, has been rarely reported after this vaccine is given. If you experience any weakness or tingling in the legs, arms, or upper body, contact your doctor. Most people recover fully from GBS.

Immune system: As with any vaccine, influenza vaccine may not be as effective for those who have a weakened immune system (e.g., people on chemotherapy, people who have had an organ transplant, or people with HIV).

Vaccine protection: As with any vaccine, this vaccine may not protect 100% of people who receive it. The vaccine only provides protection against certain strains of the flu virus – the ones from which it was prepared (or ones that are closely related).

Pregnancy: If you are or may become pregnant while receiving this medication, talk to your doctor about the risks and benefits of using this vaccine. The National Advisory Committee on Immunization recommends influenza vaccination for healthy pregnant women.

Breast-feeding: Breast-feeding mothers can receive the influenza vaccination.

Children: The influenza vaccine is not recommended in children under 6 months of age.

What other drugs could interact with this medication?

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

  • acetaminophen
  • immunosuppressive therapy (e.g., some medications used for the treatment of cancer or for transplant recipients)
    • azathioprine
    • belimumab
    • 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

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.