Isoniazid
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Drug Status
Government Approvals
US(FDA), UK(BNF)
WHO Essential Medicine
NO
Known Teratogen
No
Pharmaceutical Class
Antimycobacterial
Controlled Drug Substance
No
Isoniazid
Summary
Isoniazid is an antibiotic that is used to prevent and treat tuberculosis (TB). This includes both active TB infections and latent TB, to reduce the risk of developing active disease.
Isoniazid works by killing the bacteria that cause TB. It interferes with the bacteria's ability to form essential components of their cell wall, stopping their growth.
For adults, the dosage is 5 mg/kg up to 300 mg once daily. For children, it's 10-15 mg/kg up to 300 mg once daily. Always follow your doctor's instructions.
Common side effects include nausea, abdominal pain, and fatigue. Rare but serious risks include liver damage and nerve inflammation. Always notify your doctor if you notice any unusual symptoms.
People with active liver disease, a history of severe reactions to Isoniazid, or certain medical conditions should avoid it. Always discuss your medical history with your doctor. Avoid alcohol as it increases the risk of liver damage.
Indications and Purpose
How does Isoniazid work?
Isoniazid works by inhibiting the synthesis of mycolic acids, which are vital components of the bacterial cell wall in Mycobacterium tuberculosis. This action effectively kills the bacteria, helping to treat and prevent tuberculosis.
Is Isoniazid effective?
Isoniazid is an effective antituberculosis agent that works by killing the bacteria causing tuberculosis. It is used in combination with other drugs to treat active TB and as a preventive measure for latent TB.
What is Isoniazid?
Isoniazid is an antituberculosis medication used to treat and prevent tuberculosis. It works by inhibiting the synthesis of mycolic acids, essential components of the bacterial cell wall, effectively killing the bacteria.
Directions for Use
For how long do I take Isoniazid?
Isoniazid is typically prescribed for a duration of 6 months or longer, depending on the condition being treated and the patient's response to the medication. Always follow your doctor's guidance on the duration of use.
How do I dispose of Isoniazid?
If you can, bring unused medicines to a drug take-back program or collection site at a pharmacy or hospital. They will dispose of this medicine properly so they don't harm people or the environment. If you can't find a take-back program, you can throw most medicines in the trash at home. But first, take them out of their original containers, mix them with something undesirable like used coffee grounds, seal the mixture in a plastic bag and throw it away.
How do I take Isoniazid?
Isoniazid should be taken on an empty stomach, either 1 hour before or 2 hours after meals. Avoid foods high in tyramine and histamine, such as certain cheeses and red wine, as they can interact with the medication.
How long does it take for Isoniazid to start working?
Isoniazid begins to work within 1 to 2 hours after oral administration, reaching peak blood levels. However, the full therapeutic effect may take weeks to months, depending on the condition being treated.
How should I store Isoniazid?
Store Isoniazid in its original container, tightly closed, at room temperature away from excess heat and moisture. Keep it out of reach of children and do not store it in the bathroom.
What is the usual dose of Isoniazid?
For adults, the usual daily dose of Isoniazid is 5 mg/kg up to 300 mg daily in a single dose. For children, the dose is typically 10 mg/kg to 15 mg/kg up to 300 mg daily in a single dose. Always follow your doctor's specific instructions.
Warnings and Precautions
Can Isoniazid be taken safely while breastfeeding?
Isoniazid is present in breast milk in low concentrations and is not considered harmful to nursing infants. However, monitoring for any adverse effects is advised, and pyridoxine supplementation may be considered.
Can Isoniazid be taken safely while pregnant?
Isoniazid should be used during pregnancy only if the benefits outweigh the risks. It crosses the placenta, and while no strong evidence of fetal harm exists, careful monitoring is advised. Pyridoxine supplementation is recommended.
Can I take Isoniazid with other prescription drugs?
Isoniazid can interact with acetaminophen, carbamazepine, phenytoin, and theophylline, among others, potentially increasing their toxicity. Always inform your doctor of all medications you are taking to avoid harmful interactions.
Does Isoniazid have adverse effects?
Adverse effects are unwanted or harmful effects caused by a medicine. Isoniazid can cause liver damage, which is serious and requires immediate medical attention. Other adverse effects include numbness or tingling in the hands and feet, which is less common. Some people might experience nausea or fatigue. Rarely, it can cause severe allergic reactions. It's important to report any new or worsening symptoms to your healthcare provider and not stop the medication without their guidance.
Does Isoniazid have any safety warnings?
Isoniazid has safety warnings, mainly about liver damage. It's important because it can cause serious liver problems. Watch for symptoms like yellowing of the skin or eyes, dark urine, or severe fatigue, which can indicate liver issues. Another warning is about nerve damage, which can cause numbness or tingling in the hands and feet. Taking vitamin B6 can help prevent this. Always inform your doctor about any new symptoms and follow their advice closely.
Is Isoniazid addictive?
Isoniazid is not addictive and has no known potential for dependence. It does not cause physical or psychological dependence, so there are no specific behaviors or warning signs to watch for in terms of addiction. It's important to take it exactly as prescribed by your healthcare provider to ensure its effectiveness in treating tuberculosis. Always follow your doctor's instructions and complete the full course of treatment.
Is Isoniazid safe for the elderly?
Elderly patients may have an increased risk of liver damage when taking Isoniazid. Regular monitoring of liver function is recommended, and any signs of liver issues should be reported to a doctor immediately.
Is it safe to drink alcohol while taking Isoniazid?
Drinking alcohol while taking Isoniazid can increase the risk of liver damage. It is advised to avoid alcohol consumption during treatment to ensure safety and effectiveness.
Is it safe to exercise while taking Isoniazid?
Most people tolerate Isoniazid well, and it should not limit your ability to exercise. However, if you experience symptoms like fatigue or dizziness, which can occasionally occur, you might need to adjust your exercise routine. It's important to listen to your body and avoid strenuous activities if you feel unwell. If you have concerns about exercising while on Isoniazid, consult your healthcare provider for personalized advice.
Is it safe to stop Isoniazid?
Isoniazid is used to treat tuberculosis, which is an infection. Stopping it suddenly can lead to the infection not being fully treated, which can cause the bacteria to become resistant to the medication. This makes the infection harder to treat and can lead to serious health problems. There are no known withdrawal symptoms, but the risk of the infection worsening is significant. Always consult your doctor before stopping Isoniazid to ensure it's safe and appropriate for your situation.
What are the most common side effects of Isoniazid?
A side effect is an unwanted reaction to a medicine. Common side effects of Isoniazid include nausea, fatigue, and numbness or tingling in the hands and feet. Some people might experience mild headaches or dizziness. It's important to note that new symptoms can occur when starting any medicine, and they might not be related to the medicine itself. Always talk to your healthcare provider before stopping any medication, as they can help determine the cause of new symptoms.
Who should avoid taking Isoniazid?
Isoniazid can cause severe liver damage, especially in those with pre-existing liver conditions or who consume alcohol. It is contraindicated in patients with severe hypersensitivity reactions or previous isoniazid-induced liver injury.
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