What does it do?

Isoniazid is an antibiotic used with other medicines 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 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 best to take it on an empty stomach if possible, one hour before or two hours after food.

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?

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including 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 Seizures	Tell your doctor immediately
Numbness or tingling of the fingers or toes	Tell your doctor
Stomach upset	Tell your doctor if troublesome

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

Other information:

• Limit alcohol intake while taking isoniazid. Alcohol may increase the risk of liver problems.
• You will need regular blood tests while taking isoniazid to check if it is causing problems with your liver.
• Your doctor will prescribe pyridoxine (vitamin B6) to help prevent side effects of isoniazid.