Flublok Quadrivalent is a vaccine used to prevent infection caused by influenza virus.

Influenza (commonly known as "the flu") is a serious infection caused by the influenza virus. Influenza virus can spread from one person to another through small droplets of saliva that are expelled into the air when an infected person coughs or sneezes. The virus can also be passed through contact with objects the infected person has touched, such as a door handle or other surfaces.

The injectable Flublok Quadrivalent (flu shot) contains recombinant proteins of the four strains of influenza virus specified by health authorities for inclusion in the annual seasonal vaccine. The proteins are non-infectious and cannot cause influenza.

Flublok Quadrivalent works by stimulating the immune system to produce antibodies that help protect against the influenza viruses carrying the proteins contained in the vaccine. It does not prevent other respiratory infections.

This medicine will not treat an active infection that has already developed in the body.

Flublok Quadrivalent is for use in adults who are at least 18 years of age.

Like any vaccine, Flublok Quadrivalent may not provide protection from disease in every person. This vaccine will not prevent illness caused by avian flu ("bird flu").

Becoming infected with influenza is much more dangerous to your health than receiving this vaccine. Influenza causes thousands of deaths each year, and hundreds of thousands of hospitalizations. However, like any medicine, this vaccine can cause side effects, but the risk of serious side effects is extremely low.

Before taking this medicine

You may not be able to receive this vaccine if you have:

• a history of severe allergic reaction to a flu vaccine; or

• a history of Guillain-Barre syndrome (within 6 weeks after receiving a flu vaccine).

Tell your doctor if you have ever had:

• bleeding problems;

• a neurologic disorder or disease affecting the brain (or if this was a reaction to a previous vaccine);

• seizures;

• a weak immune system caused by disease, bone marrow transplant, or by using certain medicines or receiving cancer treatments.

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

The Centers for Disease Control and Prevention recommends that pregnant women get a flu shot during any trimester of pregnancy to protect themselves and their newborn babies from flu. The nasal spray form of influenza vaccine is not recommended for use in pregnant women.

It may not be safe to breastfeed while using Flublok Quadrivalent. Ask your doctor about any risk.

This vaccine should not be given to anyone younger than 18 years of age.

Some brands of influenza vaccine are made for use in adults and not in children. Your child's doctor can recommend the best influenza vaccine for your child.

This vaccine is given as an injection (shot) into a muscle. You will receive this injection in a doctor's office or other clinic setting.

You should receive a flu vaccine every year. Your immunity will gradually decrease over the 12 months after you receive the Flublok Quadrivalent.

The Flublok Quadrivalent is usually given in October or November. Some people may need to have their vaccines earlier or later. Follow your doctor's instructions.

Your doctor may recommend treating fever and pain with an aspirin-free pain reliever such as acetaminophen (Tylenol) or ibuprofen (Motrin, Advil, and others) when the shot is given and for the next 24 hours.

You may not be able to receive this vaccine if you have:

• a history of severe allergic reaction to a flu vaccine; or

• a history of Guillain-Barre syndrome (within 6 weeks after receiving a flu vaccine).

Tell your doctor if you have ever had:

• bleeding problems;

• a neurologic disorder or disease affecting the brain (or if this was a reaction to a previous vaccine);

• seizures;

• a weak immune system caused by disease, bone marrow transplant, or by using certain medicines or receiving cancer treatments.

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

The Centers for Disease Control and Prevention recommends that pregnant women get a flu shot during any trimester of pregnancy to protect themselves and their newborn babies from flu. The nasal spray form of influenza vaccine is not recommended for use in pregnant women.

It may not be safe to breastfeed while using Flublok Quadrivalent. Ask your doctor about any risk.

This vaccine should not be given to anyone younger than 18 years of age.

Since flu shots are usually given only one time per year, you will most likely not be on a dosing schedule. Call your doctor if you forget to receive your yearly flu shot in October or November.

An overdose of this vaccine is unlikely to occur.

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

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

Keep track of any and all side effects you have after receiving this vaccine. If you ever need to receive Flublok Quadrivalent in the future, you will need to tell your doctor if the previous shot caused any side effects.

Influenza virus injectable (killed virus) vaccine will not cause you to become ill with the flu virus that it contains. However, you may have flu-like symptoms at any time during flu season that may be caused by other strains of influenza virus.

Call your doctor at once if you have:

• a light-headed feeling, like you might pass out;

• severe weakness or unusual feeling in your arms and legs (may occur 2 to 4 weeks after you receive the vaccine);

• high fever;

• seizure (convulsions); or

• unusual bleeding.

Common side effects may include:

• low fever, chills;

• mild fussiness or crying;

• redness, bruising, pain, swelling, or a lump where the vaccine was injected;

• headache, tired feeling; or

• joint or muscle pain.

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.

If you are using any of these medications, you may not be able to receive the vaccine, or may need to wait until the other treatments are finished:

• phenytoin, theophylline, or warfarin (Coumadin, Jantoven);

• an oral, nasal, inhaled, or injectable steroid medicine;

• medications to treat psoriasis, rheumatoid arthritis, or other autoimmune disorders--azathioprine, etanercept, leflunomide, and others; or

• medicines to treat or prevent organ transplant rejection--basiliximab, cyclosporine, muromonab-CD3, mycophenolate mofetil, sirolimus, tacrolimus.

This list is not complete. Other drugs may affect Flublok Quadrivalent, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.