This medication belongs to a group of medications called vaccines. It is used to prevent hepatitis A and hepatitis B infections by helping your body produce its own protection (antibodies or immunity) against the infection. Hepatitis A and hepatitis B are major causes of serious liver diseases such as viral hepatitis, cirrhosis, and primary hepatocellular carcinoma (liver cancer). This vaccine does not provide protection against infections caused by other agents such as hepatitis C or E.

This vaccine is recommended for people one year old and older, especially those at increased risk of infection with the hepatitis A and hepatitis B virus. These include but are not restricted to:

• health care professionals
• patients and patient contacts in certain hospital clinics (e.g., dialysis, cancer)
• sewage workers
• daycare employees
• military personnel
• people travelling to areas where hepatitis A and hepatitis B are common
• people who have multiple sexual partners
• people who use illicit injectable drugs
• people working or living in institutions

A qualified health professional will inject the vaccine.

The standard dose for adults 19 years and over is 1 mL and adolescents and children aged 1 to 18 years old is 0.5 mL. Doses are injected into a muscle and repeated after 1 month and 6 months, for a total of 3 doses. A qualified health professional will inject the vaccine.

For children and adolescents aged 1 to 15 years, an alternate dosing schedule of a 1 mL dose followed by a second dose after 6 to 12 months can be used. If rapid protection is needed, the standard 3-dose schedule is recommended.

In exceptional cases for adults, when travel will take place within a month or less of starting the vaccine course, an "accelerated" dosing schedule may be used: one dose is given immediately, followed by additional doses at 7 days and 21 days. A fourth dose is recommended at 12 months if this schedule is used.

In general, most people do not require a booster dose as this vaccine can provide protection for a lifetime. However, some people, such as those with weakened immune systems, may require a booster dose. Your doctor will advise you whether a booster dose is needed.

The vaccine should be refrigerated and protected from light until it is used. It must not freeze, or it will have to be discarded.

Twinrix Adult

Each 1 mL dose contains hepatitis A 720 ELISA units and hepatitis B 20 µg.

Twinrix Junior

Each 0.5 mL dose contains hepatitis A 360 ELISA units and hepatitis B 10 µg.

The liquid suspension is made isotonic with sodium chloride in water for injection. Nonmedicinal ingredients: aluminum hydroxide, aluminum phosphate, sodium chloride, and water for injection. Residues: amino acids for injection, formaldehyde, neomycin sulphate, and polysorbate 20. TWINRIX meets the World Health Organization requirements for the manufacture of biological substances.

Hepatitis A - hepatitis B vaccine should not be used by or given to anyone who:

• is sensitive or allergic to any ingredients of the medication
• are allergic to neomycin
• has a severe illness associated with fever

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.

• diarrhea
• drowsiness
• fatigue
• fever
• generally feeling unwell
• headache
• irritability or fussiness (children and infants)
• loss of appetite
• muscle aches
• nausea
• redness, pain, and swelling at the place of injection
• 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:

• dizziness
• skin rash or itchiness

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

• fainting
• signs of a severe allergic reaction (difficulty breathing or swallowing; hives; swelling of the mouth, throat, or face)

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.

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.

Dialysis and impaired immune system: This vaccine may not be as effective for people receiving hemodialysis or people with impaired immune systems.

Neomycin: There is a possibility that this vaccine contains small amounts of neomycin. People who are allergic to neomycin may experience an allergic reaction to this vaccine.

Protection from hepatitis A and hepatitis B: As with any vaccine, this vaccine may not result in total protection from hepatitis A and hepatitis B and may not prevent hepatitis A or hepatitis B for people who are infected with the virus at the time of vaccination.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while receiving this medication, contact your doctor immediately.

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

Immunosuppressant medications (e.g., medications that treat cancer or corticosteroids) may affect how this medication works or may increase the risk of side effects. 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 that 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.