Treats and prevents tuberculosis (TB).
There may be other brand names for this medicine.
When This Medicine Should Not Be Used
You should not use this medicine if you have had an allergic reaction to isoniazid or reactions such as fever, chills, or arthritis from taking this medicine. You should not use isoniazid if you have or had any liver problems.
How to Use This Medicine
- Your doctor will prescribe your exact dose and tell you how often it should be given. This medicine is given as a shot into one of your muscles.
- You may be taught how to give your medicine at home. Make sure you understand all instructions before giving yourself an injection. Do not use more medicine or use it more often than your doctor tells you to.
- Use a new needle and syringe each time you inject your medicine.
- Keep using this medicine for the full treatment time, even if you feel better after the first few doses. Your infection may not clear up if you stop using the medicine too soon.
If a dose is missed:
- This medicine needs to be given on a fixed schedule. If you miss a dose or forget to use your medicine, call your doctor or pharmacist for instructions.
How to Store and Dispose of This Medicine
- If you store this medicine at home, keep it at room temperature, away from heat and direct light.
- Keep all medicine away from children and never share your medicine with anyone.
- Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any leftover medicine, containers, and other supplies. You will also need to throw away old medicine after the expiration date has passed.
- Throw away used needles in a hard, closed container that the needles cannot poke through. Keep this container away from children and pets.
Drugs and Foods to Avoid
Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.
- Make sure your doctor knows if you are using medicine for seizures such as carbamazepine (Tegretol®), phenytoin (Dilantin®, Depakote®), or valproate.
- Make sure your doctor knows if you are using medicine such as acetaminophen, ketoconazole, or theophylline (Theo-Dur®, Slo-Bid®).
- There are many other drugs that can interact with isoniazid. Make sure your doctor knows about all other medicines you are using.
- Do not drink alcohol while you are using this medicine.
Warnings While Using This Medicine
- Make sure your doctor knows if you are pregnant or breastfeeding, or if you have had a baby recently.
- Make sure your doctor knows if you have diabetes, HIV/AIDS, kidney disease, or liver disease.
- Make sure your doctor knows if you have ever used this medicine before.
- Your doctor will need to check your blood at regular visits while you are using this medicine. Be sure to keep all appointments.
Possible Side Effects While Using This Medicine
Call your doctor right away if you notice any of these side effects:
- Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
- Blurred vision or eye pain.
- Dark-colored urine or pale stools.
- Drowsiness, seizures or fainting.
- Nausea, vomiting, loss of appetite, or pain in your upper stomach.
- Numbness, tingling, or burning pain in your hands, arms, legs, or feet.
- Unusual bleeding, bruising, or weakness.
- Yellowing of your skin or the whites of your eyes.
If you notice these less serious side effects, talk with your doctor:
- Dry skin.
- Loss of memory.
- Mild skin rash.
- Pain, itching, burning, swelling, or a lump under your skin where the shot is given.
- Pale skin or pale lip color.
- Swelling in your armpits, neck, or thigh.
If you notice other side effects that you think are caused by this medicine, tell your doctor
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088
- Last Reviewed on 06/12/2013
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This page was last updated: June 18, 2013