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Isoniazid

Drug Class: Commonly Known As: Category:
Antitubercular Adult, Children

Isoniazid - Side Effects, Precautions, and Contraindications

What side effects can Isoniazid cause?

You may experience numbness or tingling sensations on your hands and feet.

  • Continue taking your medication and inform your doctor at your next visit. Your doctor may advise you to take Pyridoxine (Vitamin B6) to prevent or lessen this side effect.

If you experience any of these symptoms, you should stop your medication and seek immediate medical attention:

  • Drug allergy symptoms such as swollen face/eyes/lips/tongue, difficulty in breathing, itchy skin rashes over your whole body
  • Signs of liver issues such as dark coloured urine or light coloured stools, nausea and vomiting that does not go away, loss of appetite, stomach pain, yellowing of your eyes or skin
  • Fever, chills, feeling tired or weak (flu-like symptoms)
  • Unexplained bruising or bleeding

There are some tests that are required to better monitor and manage possible side effects from treatment of tuberculosis. These include:

  • Regular blood tests, especially to monitor your liver function

Before taking Isoniazid , what precautions must I follow?

​Before starting TB treatment, inform your healthcare professional if:

  • You are allergic to this medication or any of the other ingredients of this medication.
  • You have pre-existing medical conditions such as kidney and/or liver problems, gout.
  • You consume alcohol regularly.
  • You intend to become pregnant (conceive) or breastfeed while taking this medication.
  • You are pregnant or breastfeeding.
  • If you have active TB, you should stay at home for the first two weeks of your treatment. This is to prevent spreading the bacteria to others, as you are more likely to be able to infect others during this period. If you have close, regular contact with family members or friends, encourage them to visit a doctor to test for TB.
  • If you need to leave the house, wear a surgical mask in public spaces and avoid crowded places. Avoid close contact with anyone who may have low immunity (including elderly, young children, pregnant women).
  • After taking at least two weeks of effective treatment, you are generally considered non-infectious, meaning less likely to infect others, provided that you continue with the rest of the treatment.
  • If you have latent TB, seeing a doctor early and receiving treatment can help to prevent your loved ones from getting active TB in the future.

What food or medicine must I avoid when I take Isoniazid ?

  • ​Avoid alcohol as it may increase the risk of liver problems.
  • It is important that you inform your healthcare provider if you are taking other medications – including those for current medical conditions, chronic medications, oral contraceptives (birth control pills), over-the-counter medications, supplements and traditional/herbal remedies – as they may interact with TB medications.
  • Updated on Saturday, August 31, 2019
  • Article contributed by PSS National Medication Information Workgroup PSS National Medication Information Workgroup

    The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth

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