Adult Medication

Brand Names: Canada

Dom-Isoniazid; Isotamine; PDP-Isoniazid


  • Very bad and sometimes deadly liver problems have happened with this drug. Call your doctor right away if you have signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
  • The chance of liver problems is higher the older you are. The chance may also be raised by drinking alcohol every day, long-term liver problems, or injection drug use. The chance of liver problems may also be raised in women, mainly women who are black or Hispanic or who have just had a baby. Most of the time, liver problems caused by this drug happen within the first 3 months of care, but they can happen at any time. Talk with the doctor.
  • You will be watched closely by your doctor.
  • If you have active liver disease, talk with your doctor. This drug may not be right for you.

What is this drug used for?

  • It is used to treat TB (tuberculosis).
  • It is used to prevent TB (tuberculosis).

What do I need to tell my doctor BEFORE I take this drug?

  • If you have an allergy to isoniazid or any other part of this drug.
  • If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
  • If you have had very bad side effects while taking isoniazid in the past, like liver problems, drug fever, chills, or arthritis.
  • If you had liver problems while taking some other drug in the past.
This is not a list of all drugs or health problems that interact with this drug.
Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this drug with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take this drug?

  • Tell all of your health care providers that you take this drug. This includes your doctors, nurses, pharmacists, and dentists.
  • Talk with your doctor before you drink alcohol.
  • Take vitamin B6 (pyridoxine) as you were told by your doctor.
  • If you have high blood sugar (diabetes), you will need to watch your blood sugar closely.
  • Have blood work checked as you have been told by the doctor. Talk with the doctor.
  • Have an eye exam as you have been told by your doctor.
  • Some foods and drinks like cheese and red wine, when taken with this drug, may cause very risky effects such as sudden high blood pressure. To avoid these problems, get a list of foods to avoid.
  • This drug may affect how much of some other drugs are in your body. If you are taking other drugs, talk with your doctor. You may need to have your blood work checked more closely while taking this drug with your other drugs.
  • A very bad and sometimes deadly reaction has happened with this drug. Most of the time, this reaction has signs like fever, rash, or swollen glands with problems in body organs like the liver, kidney, blood, heart, muscles and joints, or lungs. Talk with the doctor.
  • Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using this drug while you are pregnant.
  • Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:
  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of high blood sugar like confusion, feeling sleepy, more thirst, more hungry, passing urine more often, flushing, fast breathing, or breath that smells like fruit.
  • Signs of lupus like a rash on the cheeks or other body parts, sunburn easy, muscle or joint pain, chest pain or shortness of breath, or swelling in the arms or legs.
  • Signs of a pancreas problem (pancreatitis) like very bad stomach pain, very bad back pain, or very bad upset stomach or throwing up.
  • Signs of too much acid in the blood (acidosis) like confusion; fast breathing; fast heartbeat; a heartbeat the does not feel normal; very bad stomach pain, upset stomach, or throwing up; feeling very sleepy; shortness of breath; or feeling very tired or weak.
  • A burning, numbness, or tingling feeling that is not normal.
  • Seizures.
  • Feeling confused.
  • Memory problems or loss.
  • Change in eyesight.
  • Mood changes.
  • Fever or chills.
  • Joint pain or swelling.
  • Any unexplained bruising or bleeding.
  • Feeling very tired or weak.
  • Enlarged breasts.
  • A very bad skin reaction (toxic epidermal necrolysis) may happen. It can cause very bad health problems that may not go away, and sometimes death. Get medical help right away if you have signs like red, swollen, blistered, or peeling skin (with or without fever); red or irritated eyes; or sores in your mouth, throat, nose, or eyes.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

All products:

  • Upset stomach or throwing up.


  • Irritation where the shot is given.
These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.
You may report side effects to your national health agency.

How is this drug best taken?

Use this drug as ordered by your doctor. Read all information given to you. Follow all instructions closely.

All products:

  • To gain the most benefit, do not miss doses.

All oral products:

  • Take on an empty stomach. Take 1 hour before or 2 hours after meals.
  • Keep taking this drug as you have been told by your doctor or other health care provider, even if you feel well.

Liquid (syrup):

  • Measure liquid doses carefully. Use the measuring device that comes with this drug. If there is none, ask the pharmacist for a device to measure this drug.


  • It is given as a shot into a muscle.

What do I do if I miss a dose?

All oral products:

  • Take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.


  • Call your doctor to find out what to do.

How do I store and/or throw out this drug?

All oral products:

  • Store at room temperature.
  • Store in a dry place. Do not store in a bathroom.
  • Protect from light.


  • If you need to store this drug at home, talk with your doctor, nurse, or pharmacist about how to store it.

All products:

  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Check with your pharmacist about how to throw out unused drugs.

General drug facts

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else’s drugs.
  • Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
  • Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
  • Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Consumer Information Use and Disclaimer

This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.

Last Reviewed Date



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