Isoniazid Pediatric Fact Sheet

Medication Information

Isoniazid is an antibiotic medication. It is used to treat Tuberculosis (TB) disease along with other medications. Isoniazid is also used to treat Tuberculosis Infection (TBI). 

The TB germs (bacteria) are very strong and are hard to get rid of. You will need to give this medication to your child for six to 12 months to kill the TB bacteria. Your healthcare provider will decide how many months your child will need to take the medication.

Taking the Medication

• It is important to give this medication to your child every day at the same time, for example, always before going to bed or always first thing in the morning.
• This medication works best on an empty stomach (one hour before or two hours after a meal). However, if it upsets your child’s stomach, you may give it with a small snack.
• Your child must take the medication for the length of time that it is prescribed.
• Even if your child starts to feel better, it is important for them to keep taking this medication until their healthcare provider tells you to stop giving the medication to your child. Contact your healthcare provider immediately if you stop giving the medication.
• See your healthcare provider on a regular basis while your child is taking this medication and follow instructions regarding blood work.
• Your child’s doctor may recommend that your child also takes vitamin B6 (Pyridoxine). Vitamin B6 helps prevent numbness and tingling in fingers and toes which may be caused by Isoniazid.

Possible Side Effects

Contact your healthcare provider immediately if your child experiences any of the following side effects:

• Painful or tingling feeling in fingers or toes
• Skin rash
• Loss of appetite
• Nausea, vomiting
• Stomach cramps and pain
• Dark urine
• Yellowing of the skin or eyes
• Unexplained fatigue, tiredness, weakness

Other possible side effects include:

• Heartburn
• Diarrhea (can occur with liquid medication)
• Fever
• Difficulty with speech, inability to concentrate or altered mood
• Headache
• Mild hair loss
• Flushing (if flushing occurs avoid aged cheeses, cured meats, fermented cabbage (e.g. sauerkraut), soya sauce, fish or shrimp sauce, yeast-extract spreads (e.g., marmite), broad bean pods (e.g., fava beans)

If you are concerned about these or any other side effects, call your healthcare provider.

Precautions

• Keep regular appointments with your child’s healthcare provider while taking this medication.
• Talk to your healthcare provider about other medications your child is taking or any new medications that your child starts taking including any drugs, vitamins, minerals, natural supplements, or alternative medicines since Isoniazid can alter the effects of certain medication.
• Do not share this medication with anyone.

Drug Interactions

• Foods that are high in fat or sugars such as glucose, fructose and sucrose decrease how well the medication works.

Missed Doses

• If you miss a dose, give it as soon as possible. If it is almost time to give the next dose, do not give the missed dose. Do not give two doses at the same time.

Tips for Giving your Child Liquid Medication

• Measure the dose in the medication cup that was provided.
• Give the medication to your child in small amounts and watch them swallow it before you give them more.
• We recommend you don’t mix the medication with food or drinks. If you must mix the medication with food or drink, use a very small amount so that the child will finish it all and you know the full dose has been taken.

Tips for Giving your Child Pills

• Pills can be crushed and mixed with water or small amounts of food. Use sugar-free, low-fat foods such as sugar-free pudding, baby food or yogurt.

Storage

• Store the medication at room temperature in a cool dry place. Do not put in the refrigerator.  Keep out of reach and sight of children.

A public health nurse will contact you on a regular basis while your child is taking Isoniazid.

For further information, please contact the Communicable Disease Control Program at 705-474-1400 or toll free at 1-800-563-2808, ext. 5229 or email us at cdc@healthunit.ca.

References

1. Pendopharm, Division de/of Pharmascience Inc. (2020). Prescribing Information pdp-Isoniazid Isoniazid Tablets USP 50mg, 100mg, 300mg, Isoniazid Oral Solution USP 50mg/5mL. Retrieved from: https://pdf.hres.ca/dpd_pm/00059225.PDF.
2. James C. Johnston, Ryan Cooper & Dick Menzies (2022) Chapter 5: Treatment of tuberculosis disease, Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 6:sup1, 66-76, DOI: https://www.tandfonline.com/doi/full/10.1080/24745332.2022.2036504 
3. The Hospital for Sick Children. (2014). Medicines video: how to give your child liquid medicines at home. Retrieved from https://www.youtube.com/watch?v=Q0ewm7bgtTA

Created, Sep 2026, by CDC