Health Library

Isoniazid (By injection)

Isoniazid (eye-soe-NYE-a-zid)

Treats and prevents tuberculosis (TB).

Brand Name(s):

When This Medicine Should Not Be Used:

How to Use This Medicine:

Injectable

• 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.
• Take all of the medicine in your prescription to clear up your infection, even if you feel better after the first few doses.
• It is best to use this medicine on an empty stomach.
• Missed dose: You must use this medicine on a fixed schedule. Call your doctor or pharmacist if you miss a dose.
• If you store this medicine at home, keep it at room temperature, away from heat and direct light.
• Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any leftover medicine, containers, and other supplies. 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.

• Some medicines and foods can affect how isoniazid works. Tell your doctor if you are using any of the following:
  • Acetaminophen
  • Ketoconazole
  • Medicine for seizures, such as carbamazepine, phenytoin, or valproate
  • Theophylline

Warnings While Using This Medicine:

• Tell your doctor if you are pregnant or breastfeeding, or if you had a baby recently. Also tell your doctor if you have diabetes, HIV/AIDS, kidney disease, liver disease, or peripheral neuropathy.
• Tell your doctor if you drink alcohol daily or inject street drugs, because you have a higher risk for liver disease while you use this medicine.
• Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
• Keep all medicine out of the reach of children. Never share your medicine with anyone.

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 urine or pale stools, nausea, vomiting, loss of appetite, pain in your upper stomach, yellow skin or eyes
• Numbness, tingling, or burning pain in your hands, arms, legs, or feet
• Seizures or fainting
• Unusual bleeding, bruising, or weakness

If you notice these less serious side effects, talk with your doctor:

• Mild skin rash
• Pain, itching, burning, swelling, or a lump under your skin where the shot is given

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 Updated: 9/6/2024