What does it do?

Isoniazid and rifampicin is an antibiotic used to treat or prevent tuberculosis (TB).

Before you start

• Tell your doctor if you have liver problems, or if you have ever had a seizure.
• Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.

How should you take it?

Take isoniazid and rifampicin regularly as directed with a glass of water. It is best to take it on an empty stomach if possible, one hour before or two hours after food. Keep taking it until the course is finished.
It is important to take it regularly. If you often forget to take it, it may not work as well.

What if you forget a dose?

If it is nearly time for your next dose, skip the missed dose and take your next dose at the usual time. Otherwise, take the missed dose as soon as you remember. Do not take two doses at the same time.

Can you take other medicines?

Rifampicin can react with many medicines, sometimes with severe results.

Remember to tell your pharmacist or doctor you are taking rifampicin before starting any other medicines or treatments, including over-the-counter medicines, vitamins, herbal products or recreational drugs.

What side effects might you notice?

Side Effects	Recommended action
Symptoms of liver problems including: yellow skin or eyes, itching, dark urine, pale bowel motions, abdominal pain Reduced number of blood cells that help your blood to clot - symptoms include: easy or unusual bruising or bleeding Seizures	Tell your doctor immediately
Numbness or tingling of the fingers or toes Skin rash, itching, flushing	Tell your doctor
Flu-like symptoms (fever, chills, aches and pains, nausea, headache, tiredness or weakness) Stomach upset	Tell your doctor if troublesome
Change in colour of body fluids e.g. urine, sweat, tears (red/orange)	This is harmless. Soft contact lenses may be stained.

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

• Limit alcohol intake while taking isoniazid and rifampicin. Alcohol may increase the risk of liver problems.
• You will need regular blood tests while taking isoniazid and rifampicin to check if it is causing problems with your liver.
• Some contraceptives may not work as well while you are taking isoniazid and rifampicin, and for 4 weeks after stopping. Discuss with your doctor or pharmacist.
• Your doctor will prescribe pyridoxine (vitamin B6) to help prevent side effects of isoniazid.