Generic name: cycloserine
Brand name: Seromycin
Dosage form: oral capsule (250 mg)
Drug class: Streptomyces derivatives

Medically reviewed by  A Ras MD.

What is cycloserine?

Cycloserine is a prescription medicine that is used to treat TB (tuberculosis). It is used to treat a urinary tract infection (UTI).


Seromycin (Cycloserine Capsules, USP), 3-isoxazolidinone, 4-amino –, (R)– is a broad–spectrum antibiotic that is produced by a strain of Streptomyces orchidaceus and has also been synthesized. Cycloserine is a white to off–white powder that is soluble in water and stable in alkaline solution. It is rapidly destroyed at a neutral or acid pH.

Cycloserine has a pH between 5.5 and 6.5 in a solution containing 100 mg/mL. The molecular weight of cycloserine is 102.09, and it has an empirical formula of C3H6N2O2.


Before taking cycloserine, tell your doctor:

  • If you are allergic to cycloserine; any part of this medicine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
  • If you have any of these health problems: Anxiety, low mood (depression), psychosis, any other mood problem, or seizures.
  • If you have kidney disease.
  • If you drink alcohol or take any drugs that have alcohol.
  • If you are breast-feeding or plan to breast-feed.

This is not a list of all drugs or health problems that interact with cycloserine.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take cycloserine with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take cycloserine?

  • Tell all of your health care providers that you take cycloserine. This includes your doctors, nurses, pharmacists, and dentists.
  • Avoid driving and doing other tasks or actions that call for you to be alert until you see how cycloserine affects you.
  • Avoid drinking alcohol while taking cycloserine.
  • Do not use longer than you have been told. A second infection may happen.
  • Have blood work checked as you have been told by the doctor. Talk with the doctor.
  • Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using cycloserine while you are pregnant.

How is cycloserine best taken?

Use cycloserine as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • Keep taking cycloserine as you have been told by your doctor or other health care provider, even if you feel well.

What do I do if I miss a dose?

  • Take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.

What are the side effects of cycloserine that I need to call my doctor about immediately?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • New or worse behavior or mood changes like depression or thoughts of killing yourself.
  • Feeling confused.
  • Memory problems or loss.
  • Dizziness or passing out.
  • Seizures.
  • Feeling sleepy.
  • Headache.
  • Change in speech.
  • Shakiness.
  • Muscle weakness.
  • Shortness of breath, a big weight gain, or swelling in the arms or legs.
  • Feeling very tired or weak.
  • A burning, numbness, or tingling feeling that is not normal.

What are some other side effects of cycloserine?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if you have any side effects that bother you or do not go away.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at

If overdose is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out cycloserine?

  • Store at room temperature.
  • Store in a dry place. Do not store in a bathroom.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.




  • SEROMYCIN  cycloSERINE Capsules, USP  250mg  THE CHAO CENTER  NDC 13845-1200-3  40 capsules Rx only
  • Usual Initial Adult Dose: One capsule (250 mg) twice a day at 12 hour intervals. See accompanying literature. Dispense in a tight container.
    WARNING: Potent drug. May cause serious reactions in some individuals. Use in patients under close medical supervision. Read accompanying literature before using.
    Keep tightly closed. Store at controlled room temperature, 20 degrees  to 25 degrees C (68 degrees to 77 degrees F). [see USP]
    Maunfacture  The Chao center for Industrial Pharmacy and Contract Manufacturing, West Lafayette, IN 47906, USA
    Expiration Date  Batch No.



Imprint CHAO F04 CHAO F04 - cycloserine 250 mg