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Isonarif (Generic Isoniazid)

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Risks of taking isoniazid (INH):

  • Hepatotoxicity: Isoniazid can cause liver damage in rare cases. Regular monitoring of liver function is essential during treatment.
  • Peripheral Neuropathy: Isoniazid can lead to nerve damage, resulting in tingling, numbness, or pain in the hands or feet. Taking vitamin B6 (pyridoxine) alongside isoniazid can help reduce this risk.
  • Drug Interactions: Isoniazid may interact with other medications, potentially affecting their effectiveness or increasing the risk of side effects. It’s important to inform your healthcare provider about all the medications you are taking to avoid harmful interactions.
  • Allergic Reactions: Although uncommon, some individuals may experience allergic reactions to isoniazid. Immediate medical attention should be sought if any signs of an allergic reaction occur.
  • Other Side Effects: Isoniazid can cause gastrointestinal disturbances, dizziness, headache, blurred vision, and psychiatric symptoms such as mood changes, depression, or psychosis. These side effects are generally uncommon but should be reported to your healthcare provider if experienced.

Why is this medication prescribed?

Isoniazid (INH) is a medication primarily used in the treatment of tuberculosis (TB). It is an antibiotic that works by inhibiting the growth and reproduction of the bacteria that cause TB. Isoniazid is considered one of the most effective drugs for the treatment of TB and is often prescribed as part of a combination therapy regimen. Key points regarding the prescription of isoniazid for TB treatment include:

  • Active Tuberculosis: Isoniazid is commonly prescribed as part of a combination therapy regimen for active TB disease, along with other TB medications. This combination helps to effectively treat the infection and prevent the development of drug resistance.
  • Latent Tuberculosis: In cases of latent TB infection, where individuals have been exposed to TB but do not have active disease or symptoms, isoniazid may be prescribed as a preventive measure. It aims to prevent the latent infection from progressing to active TB disease.

How should this medicine be used?

When using isoniazid, it’s important to follow the instructions provided by your healthcare provider or the medication label. Here are some general guidelines for using isoniazid:

  • Dosage: Take isoniazid exactly as prescribed by your healthcare provider. The dosage can vary depending on your condition, age, weight, and other factors. Follow the prescribed dose and do not make any changes without consulting your doctor.
  • Timing: Isoniazid is usually taken once daily. It can be taken either on an empty stomach or with food, depending on your preference and any specific instructions from your healthcare provider.
  • Combination Therapy: Isoniazid is often used in combination with other antituberculosis medications. Take all prescribed medications as directed by your doctor. It is important to complete the entire course of treatment, even if you start feeling better.
  • Duration of Treatment: The duration of treatment with isoniazid can vary depending on the condition being treated. For active tuberculosis, treatment usually lasts for several months, typically six to nine months or longer. For latent tuberculosis infection, the duration may range from three to nine months. Follow your healthcare provider’s instructions regarding the duration of treatment.
  • Regular Monitoring: Your healthcare provider may recommend regular monitoring during your treatment with isoniazid. This may include blood tests to check liver function and periodic follow-up visits to assess your progress and monitor for any side effects.

It’s important to note that the information provided here is a general guideline. Always consult your healthcare provider for specific instructions and guidance on how to use isoniazid in your particular situation.

Other uses for this medicine

Isoniazid is primarily used as a medication for the treatment of tuberculosis (TB). However, it may also have some other uses, although these uses are less common and should be discussed with a healthcare professional. Some potential off-label uses of isoniazid include the treatment of latent tuberculosis infection, the prevention of tuberculosis in individuals at high risk, and the treatment of certain atypical mycobacterial infections.

What special precautions should I follow?

When taking isoniazid, it is important to follow certain precautions to ensure its safe and effective use. Here are some general precautions to consider:

  • Inform your healthcare provider about any medical conditions you have, especially liver disease, kidney disease, or a history of alcoholism.
  • Disclose all the medications, including over-the-counter drugs and supplements, that you are currently taking to your doctor, as some medications may interact with isoniazid.
  • If you are pregnant, planning to become pregnant, or breastfeeding, consult your doctor before taking isoniazid.
  • Regularly monitor your liver function, as isoniazid can cause liver damage. Inform your doctor immediately if you experience symptoms such as nausea, vomiting, fatigue, jaundice (yellowing of the skin or eyes), or dark urine.
  • Take the medication exactly as prescribed by your doctor. Do not skip doses or stop taking it without medical advice, even if you start feeling better.

What special dietary instructions should I follow?

While taking isoniazid, it’s generally recommended to avoid consuming foods and drinks that contain high levels of tyramine, such as aged cheeses, cured meats, fermented products, and certain alcoholic beverages like beer and red wine. This is because isoniazid can interfere with the breakdown of tyramine, leading to a buildup that may cause high blood pressure or other adverse reactions. It’s best to consult your healthcare provider or pharmacist for specific dietary advice tailored to your condition.

What should I do if I forget a dose?

If you miss a dose of isoniazid, take it as soon as you remember. However, if it’s close to the time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not double the dose to catch up. It’s important to try and take the medication consistently and not miss doses, as this can affect the effectiveness of the treatment.

What side effects can this medication cause?

Isoniazid can cause various side effects, although not everyone experiences them. Common side effects of isoniazid may include:

  • Gastrointestinal effects: Nausea, vomiting, loss of appetite, and abdominal pain are common side effects of isoniazid. Taking the medication with food or a glass of milk can help alleviate these symptoms.
  • Peripheral neuropathy: Isoniazid can sometimes cause tingling or numbness in the hands or feet, known as peripheral neuropathy. This side effect is more common in individuals who are malnourished, have diabetes, or consume excessive alcohol. Your healthcare provider may prescribe vitamin B6 (pyridoxine) along with isoniazid to reduce the risk of peripheral neuropathy.
  • Rash or allergic reactions: Some individuals may develop a rash or experience allergic reactions such as itching, hives, or swelling. It’s important to inform your healthcare provider if you experience any skin changes or signs of an allergic reaction.
  • Liver toxicity: Although rare, isoniazid can cause liver damage, ranging from mild elevations in liver enzymes to severe hepatitis. Symptoms of liver toxicity may include yellowing of the skin or eyes (jaundice), dark urine, fatigue, and abdominal pain. Regular monitoring of liver function tests is typically done during isoniazid treatment to detect any potential liver problems.
  • Central nervous system effects: Isoniazid can occasionally lead to central nervous system side effects such as dizziness, headache, and irritability.
  • Blood disorders: In rare cases, isoniazid can affect blood cell production, leading to anemia, low platelet count (thrombocytopenia), or low white blood cell count (leukopenia). This can increase the risk of infections or bleeding.

It’s important to note that the side effects mentioned above are not exhaustive, and there may be other possible side effects associated with isoniazid. If you experience any severe or persistent side effects while taking isoniazid, it’s crucial to contact your healthcare provider for further evaluation and guidance. They can provide specific advice based on your individual situation.

What should I know about storage and disposal of this medication?

When it comes to storage and disposal of isoniazid, here are some important points to keep in mind:


  • Store isoniazid at room temperature, away from moisture, heat, and direct light.
  • Keep the medication out of reach of children and pets.
  • Follow any specific storage instructions provided by your healthcare provider or pharmacist.


  • Do not keep unused or expired isoniazid tablets or liquid.
  • Dispose of the medication properly according to local guidelines or regulations.
  • If you are unsure how to dispose of isoniazid, consult your pharmacist or local waste disposal authority for guidance.

In case of emergency/overdose

  • In case of an emergency or suspected overdose, call your local emergency services immediately.
  • If the person affected is unconscious, having difficulty breathing, or experiencing severe symptoms, call emergency services right away.
  • If possible, provide emergency personnel with information about the medication ingested, the dose, and the time of ingestion.

What other information should I know?

  • Isoniazid should be taken exactly as prescribed by your healthcare provider. Follow the instructions on the prescription label carefully.
  • Inform your doctor about any other medications, supplements, or herbal products you are taking, as they may interact with isoniazid.
  • Avoid drinking alcohol while taking isoniazid, as it may increase the risk of liver damage.
  • It is important to complete the full course of treatment with isoniazid, even if you start feeling better. Stopping the medication early could result in the infection not being fully treated.
  • Inform your healthcare provider if you have a history of liver disease, kidney disease, epilepsy, or any other medical conditions.
  • Isoniazid may cause side effects such as nausea, vomiting, loss of appetite, dizziness, or tingling in the hands or feet. If these side effects persist or worsen, consult your doctor.

If you miss a dose of isoniazid, take it as soon as you remember. However, if it is close to the time for your next dose, skip the missed dose and resume your regular dosing schedule. Do not take a double dose to make up for a missed one.

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