Cycloserine: what it treats and what to watch for

Cycloserine is an antibiotic doctors use mainly for drug‑resistant tuberculosis. It works differently from the usual TB drugs and is usually added when first‑line medicines aren’t enough. Because it can affect the brain, the way you take it and what you watch for matters more than with many other antibiotics.

How cycloserine works and when it’s used

Cycloserine blocks bacteria from building their cell walls, so the germs that cause TB can’t survive. You’ll most often see it prescribed for multidrug‑resistant TB (MDR‑TB) or when a patient can’t tolerate standard TB drugs. Doctors pick it when the benefits outweigh the risks—especially if other options are limited.

How to take it, dosing and simple safety tips

Follow your prescriber’s instructions exactly. Typical adult dosing ranges, depending on the case, but many people take doses split twice a day. Don’t stop early even if you feel better—TB treatment needs the full course. Take it at the same times each day to stay steady in your blood. Store pills in a cool, dry place away from children.

Many clinicians give vitamin B6 (pyridoxine) alongside cycloserine. B6 can lower the risk of nerve and mood side effects. If your doctor prescribes B6, take it as directed—don’t skip it.

Missing a dose? Take it as soon as you remember unless the next dose is due soon. Don’t double up to catch up. If you miss multiple doses, call your clinic for advice—TB treatment needs consistent dosing to work well.

Renal function matters. Kidneys clear cycloserine, so dose changes may be needed if you have kidney problems. Your doctor will check blood tests and adjust the plan if needed.

Watch alcohol and sedatives. Alcohol can make brain side effects worse. Tell your doctor about any sleeping pills, antidepressants, or anti‑seizure drugs—you may need careful monitoring or dose changes.

Common side effects include headache, dizziness, and trouble sleeping. More serious effects involve mood changes, anxiety, depression, confusion, or seizures. If you notice new or worsening mood symptoms, hallucinations, or any seizure activity, seek medical help right away.

Before you start, tell your prescriber about past mental health issues, a history of seizures, pregnancy or breastfeeding, and all medicines and supplements you take. That helps prevent dangerous interactions and ensures safer monitoring.

Regular checkups make cycloserine much safer. Expect your provider to ask about mood and sleep, and to order blood tests and kidney checks. If anything feels off, report it quickly—early fixes prevent bigger problems.

Questions about buying cycloserine online or switching brands? Talk with your clinic pharmacist. Make sure any pharmacy you use is legitimate and that the product matches your prescription exactly. When in doubt, call your prescriber before changing where you get your medicine.