How do you take Cycloserine?

The usual adult dose is one 250 mg capsule taken every 12 hours (twice daily) to start, which your doctor may increase to 250 mg every 6-8 hours depending on how you respond. You can take it with or without food, but taking it with food may reduce stomach upset. Always follow your TB doctor's specific instructions.

What are the side effects of Cycloserine?

Headache and dizziness, feeling nervous or anxious, drowsiness or feeling sleepy, difficulty sleeping, slight confusion or difficulty concentrating

Who should not take Cycloserine?

People who are allergic to cycloserine, people with epilepsy or a history of seizures, people with severe depression or psychosis (serious mental health conditions), people with severe kidney problems, and heavy alcohol drinkers.

Prescription

Antibiotic (Anti-tuberculosis)

Cycloserine

Q: What is Cycloserine used for?

Tuberculosis (TB), especially drug-resistant TB when first-line TB drugs like rifampicin and isoniazid are no longer working

Last reviewed June 2026

Who is this for?

What is this drug?

Cycloserine is an antibiotic that works by stopping the growth of tuberculosis (TB) bacteria by weakening their protective wall, eventually killing them.

What is it used for?

Tuberculosis (TB)especially drug-resistant TB when first-line TB drugs like rifampicin and isoniazid are no longer working

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Tuberculosis (TB)Bacterial Infections

How it works

Inhibits bacterial cell wall synthesis by binding to D-alanyl-D-alanine synthetase and preventing the incorporation of D-alanine into peptidoglycan, thereby disrupting mycobacterial cell wall integrity.

Prescription Required

You need a doctor's prescription to buy this drug.

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What to watch out for

This is a serious prescription TB drug — never buy it from roadside sellers or use it without a doctor's supervision. Complete your full TB treatment course even if you feel better, because stopping early can create drug-resistant TB that is much harder to treat. Do not share this medication with anyone else, even if they also have TB symptoms.

Common Side Effects

Headache and dizziness
feeling nervous or anxious
drowsiness or feeling sleepy
difficulty sleeping
slight confusion or difficulty concentrating

Serious Side Effects

Seizures (convulsions or fits) — stop the drug and go to the hospital immediately. Severe mood changes
depression
or thoughts of harming yourself — tell your doctor right away. Skin rash with fever or unusual bleeding — seek urgent medical attention.

Drug Interactions

Alcohol can greatly increase the risk of seizures and worsen the nervous system side effects, so avoid drinking alcohol completely while on this drug. Isoniazid, another common TB drug, can increase the risk of dizziness and seizures when used together — your doctor will monitor you closely. Phenytoin (used for epilepsy) levels may increase when taken with cycloserine, so inform your doctor if you take it.

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Is it safe to take Cycloserine with your other drugs?

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Pregnancy & Breastfeeding Warning

Cycloserine should only be used during pregnancy or breastfeeding if your doctor decides the benefit of treating your TB outweighs the risks to the baby — always consult your doctor.

Who Should NOT Take This

People who are allergic to cycloserine
people with epilepsy or a history of seizures
people with severe depression or psychosis (serious mental health conditions)
people with severe kidney problems
and heavy alcohol drinkers.

How to Store

Store in a cool, dry place away from direct sunlight and heat — Nigerian weather can be very hot, so avoid storing near windows or in cars. Keep the container tightly closed and far away from children's reach.

For information only — not medical advice. Always talk to a doctor or pharmacist before changing your medication.