Type of medicine: antituberculosis
Generic and brand names: isoniazid, oral
This medicine is taken by mouth to treat tuberculosis infections. It is usually prescribed with other medicines.
It may also be used to prevent TB for people at high risk of infection.
This medicine may also be given by injection (shot).
It may be used for other conditions as determined by your healthcare provider.
Before taking this medicine, tell your healthcare provider if you have ever had:
Your healthcare provider may want your vision checked before you start taking this medicine and while you are taking it.
Females of childbearing age: Tell your healthcare provider if you are pregnant or plan to become pregnant while taking this medicine. It is not known whether this medicine will harm an unborn baby. Do not breast-feed without your healthcare provider's approval.
This medicine is best taken on an empty stomach 1 hour before meals or 2 hours after meals. However, you may take this medicine with food if it upsets your stomach. A liquid form is available if you cannot swallow the tablets. If you have the liquid form of this medicine, use the measuring device given to you by the pharmacist (not a common kitchen spoon) to make sure you get the right dose. The average household teaspoon may not hold the right amount of liquid.
Injections of this medicine are usually given by a healthcare provider. These shots are normally given in the muscles of the thigh, upper arms, or buttocks. You may be taught how to give yourself these shots. Make sure you understand all instructions before giving yourself a shot.
Check the label on the medicine for directions about your specific dose. Take this medicine exactly as your healthcare provider prescribes. Do not take more or less or take it longer than prescribed. Do not stop taking this medicine without your healthcare provider's approval. Keep taking it even if you feel better.
Do not use this medicine for any other infection unless your healthcare provider approves.
Your healthcare provider may instruct you to take a vitamin (pyridoxine/vitamin B-6) with this medicine to lessen its side effects.
If you miss a dose, take it as soon as you remember unless it is almost time for the next scheduled dose. In that case, skip the missed dose and take the next one as directed. Do not take double doses. If you are taking only one dose a day and you miss the dose one day, do not double the dose the next day. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your healthcare provider.
If you or anyone else has intentionally taken too much of this medicine, call 911 or go to the emergency room right away. If you pass out, have seizures, weakness or confusion, or have trouble breathing, call 911. If you think that you or anyone else may have taken too much of this medicine, call the poison control center. Do this even if there are no signs of discomfort or poisoning. The poison control center number is 800-222-1222.
Symptoms of an acute overdose may include: nausea, vomiting, dizziness, slurred speech, blurred vision, hallucinations, trouble breathing, seizures, coma.
This medicine can cause liver problems. You will need to have blood tests regularly to see how this medicine affects you. Keep all appointments for these tests. Contact your healthcare provider right away if you develop severe tiredness, nausea, vomiting, loss of appetite, dark urine, fever, headache, muscle or joint pain, yellowing of your eyes and skin. These are signs of possible liver damage.
Your healthcare provider will want to see you regularly while you are taking this medicine. You may need to have blood tests regularly to see how this medicine affects you. Keep all appointments for these tests.
Daily use of alcohol while you are taking this medicine may cause liver problems. Do not drink alcohol while you are taking this medicine.
This medicine may cause eye problems or make you dizzy. Do not drive or operate machinery unless you are fully alert and can see clearly.
If you need emergency care, surgery, or dental work, tell the healthcare provider or dentist you are taking this medicine.
Tell your healthcare provider right away if you develop blurred vision or if you have any change in your vision with or without eye pain.
Diabetics: This medicine may affect your blood sugar level and change the amount of insulin or other diabetes medicines you may need. Check your blood glucose more often while taking this medicine. Talk to your healthcare provider about this.
Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your healthcare provider if you have any side effects that continue or get worse.
Life-threatening (Report these to your healthcare provider right away. If you are unable to reach your healthcare provider right away, get emergency medical care or call 911 for help): Allergic reaction (hives; itching; rash; trouble breathing; tightness in your chest; swelling of your lips, tongue, and throat).
Serious (report these to your healthcare provider right away): Weakness; tiredness; loss of appetite; nausea; vomiting; vision changes; yellowish skin or eyes; dark urine; light-colored stools; tingling or burning of hands or feet; unusual bruising or bleeding; fever.
Other: Dizziness, stomach upset, diarrhea.
When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods may also interact. Using these products together might cause harmful side effects. Talk to your healthcare provider if you are taking:
Severe reactions may occur if you eat foods with a lot of tyramine. Use caution with the foods listed. They can cause a reaction that includes a severe headache, large pupils, neck stiffness, nausea, vomiting, diarrhea, flushing, sweating, itching, irregular heartbeat, and chest pain.
Do not drink alcohol while you are taking this medicine.
If you are not sure if your medicines might interact, ask your pharmacist or healthcare provider. Keep a list of all your medicines with you. List all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take. Be sure that you tell all healthcare providers who treat you about all the products you are taking.
Store this medicine at room temperature. Keep the container tightly closed. Protect it from heat, high humidity, and bright light.
This advisory includes selected information only and may not include all side effects of this medicine or interactions with other medicines. Ask your healthcare provider or pharmacist for more information or if you have any questions.
Ask your pharmacist for the best way to dispose of outdated medicine or medicine you have not used. Do not throw medicine in the trash.
Keep all medicines out of the reach of children.
Do not share medicines with other people.
