Generic name: Isoniazid Tablets [ eye-soe-NYE-a-zid ]
Drug class: Hydrazide derivatives
Medically reviewed by Drugs.com. Last updated on Dec 16, 2022.
- Very bad and sometimes deadly liver problems have happened with this medicine (isoniazid tablets). 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 medicine (isoniazid tablets) happen within the first 3 months of care, but they can happen at any time. Most of the time, liver function has gone back to normal but sometimes it has not. Blood work will need to be done before starting this drug and while taking it. If you have questions, talk with the doctor.
- If you have active liver disease, talk with your doctor. This medicine may not be right for you.
Uses of Isoniazid Tablets:
- 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 Isoniazid Tablets?
- If you have an allergy to isoniazid or any other part of this medicine (isoniazid tablets).
- If you are allergic to this medicine (isoniazid tablets); any part of this medicine (isoniazid tablets); or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
- 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 medicine (isoniazid tablets).
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 medicine (isoniazid tablets) 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 Isoniazid Tablets?
- Tell all of your health care providers that you take this medicine (isoniazid tablets). 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, may cause sudden, severe high blood pressure when you are taking this medicine (isoniazid tablets). This effect can be deadly. Talk with your doctor about your risk for this effect. Get a list of foods and drinks to avoid. Avoid these foods and drinks for as long as your doctor has told you after this medicine (isoniazid tablets) is stopped.
- A severe and sometimes deadly reaction has happened. 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. If you have questions, talk with the doctor.
- Tell your doctor if you are pregnant, plan on getting pregnant, or are breast-feeding. You will need to talk about the benefits and risks to you and the baby.
How is this medicine (Isoniazid Tablets) best taken?
Use this medicine (isoniazid tablets) as ordered by your doctor. Read all information given to you. Follow all instructions closely.
- Take on an empty stomach. Take 1 hour before or 2 hours after meals.
- Keep taking this medicine (isoniazid tablets) as you have been told by your doctor or other health care provider, even if you feel well.
What do I do if I miss a dose?
- 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.
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, swallowing, 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 that 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.
- Feeling confused.
- Memory problems or loss.
- Change in eyesight.
- Mood changes.
- Fever, chills, or sore throat; any unexplained bruising or bleeding; or feeling very tired or weak.
- Joint pain or swelling.
- Enlarged breasts.
- Swollen gland.
- 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 Isoniazid Tablets?
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:
- Upset stomach or throwing up.
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 the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.
If OVERDOSE is suspected:
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.
How do I store and/or throw out Isoniazid Tablets?
- Store at room temperature.
- Store in a dry place. Do not store in a bathroom.
- Protect from light.
- Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
- Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.
Consumer Information Use and Disclaimer
- 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.
- Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about this medicine (isoniazid tablets), 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.
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