Cycloserine (Seromycin) is an antibiotic that's used to treat tuberculosis (TB) and urinary tract infections (UTIs) in adults. It's usually only used for treating drug-resistant infections (when typical antibiotics don't work). This medication is a capsule that's taken by mouth. At higher doses, it can cause side effects, including sleepiness, headache, confusion, changes in personality, and even seizures. Treatment requires frequent monitoring of medication levels in the blood to prevent side effects.
Tuberculosis (TB) that's hard to treat with first-choice antibiotics
Urinary tract infections (UTIs), after first-choice options haven't worked
Cycloserine (Seromycin) is an antibiotic. It kills bacteria by preventing them from making their cell walls, which are important "shields" that bacteria use to protect themselves.
Source:Â DailyMed
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
More common
confusion
dizziness
drowsiness
increased irritability
increased restlessness
mental depression
muscle twitching or trembling
nervousness
nightmares
other mood or mental changes
speech problems
thoughts of suicide
Less common
Convulsions (seizures)
numbness, tingling, burning pain, or weakness in the hands or feet
skin rash
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
Headache
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Might be useful for hard-to-treat TB infections
Doesn't typically cause liver damage like most anti-TB antibiotics
Fewer drug interactions than other anti-TB antibiotics
Not a first-choice option for treating infections
Requires frequent blood tests to monitor medication levels in the body
Not a good option for people who have seizures or mental health problems
Before you start taking cycloserine (Seromycin), make sure your provider and pharmacist have a full list of your medications and medical history. Certain medical conditions and medications can raise your risk of nerve problems and unwanted side effects.
Cycloserine (Seromycin) might make you feel dizzy and tired. Avoid driving and doing tasks that require you to be alert until you know how the medication affects you.
Don't drink alcohol while you're taking cycloserine (Seromycin). This medication has a risk of seizures at higher doses, and drinking a lot of alcohol can raise your risk even more.
It's important to remember to take all your doses of cycloserine (Seromycin) on time. Missing or skipping doses can make the antibiotic work less well against the bacteria, which can then make the infection harder to treat. Take cycloserine (Seromycin) exactly as prescribed, finish your treatment course, and don't stop taking the antibiotic unless instructed by your provider.
Cycloserine (Seromycin) is usually prescribed with other antibiotics when it's used to treat TB to prevent drug resistance. Make sure you know which medications are part of your anti-TB treatment plan so you can start them all at the same time.
Cycloserine (Seromycin) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Risk factors: Taking over 500 mg of cycloserine (Seromycin) per day | Heavy alcohol use | Kidney problems | Also taking Trecator (ethionamide) or isoniazid
Cycloserine (Seromycin) can cause sleepiness, headache, tremor, balance problems, muscle weakness, and confusion. This medication can also cause more serious problems like seizures, depression, anxiety, psychosis, and other changes in mood or behavior.
These problems are more likely to happen if you're taking cycloserine (Seromycin) at doses higher than 500 mg per day. You're also at risk if you have kidney problems; the body can't get rid of the medication properly from the system and the medication builds up in the body. In addition, drinking large amounts of alcohol also raises the risk for seizures.
You'll need to get lab work done often so your provider can check the medication levels in your blood and monitor you for side effects. Call your provider if you have any symptoms of nervous system problems. Get medical help right away if you have a seizure while you're taking this medication.
Some people who took cycloserine (Seromycin) at very high doses (1 to 1.5 grams per day) suddenly had heart failure. This condition happens when the heart isn't able to pump as well as it should. Contact your provider right away if you notice symptoms of heart failure, such as shortness of breath that's worse with activity or when lying down, swelling in the stomach or legs, sudden weight gain, tiredness, or dizziness.
Some people who took cycloserine (Seromycin) developed low vitamin B12 levels and low folic acid levels. This can lead to anemia (low red blood cell counts). Your provider will check your vitamin levels and blood cell counts during treatment. Make sure to let your provider know if you notice any symptoms of anemia, such as tiredness, pale skin, shortness of breath, or lightheadedness.
Dosage | Quantity | Price as low as | Price per unit |
---|---|---|---|
250mg | 30 capsules | $368.04 | $12.27 |
The typical starting dose is 250 mg by mouth every 12 hours for the first 2 weeks. Your provider will adjust your dose based on the levels of cycloserine (Seromycin) in your blood. The usual dose ranges from 500 mg to 1 gram per day, separated into smaller doses throughout the day.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Tuberculosis (TB) that's hard to treat with first-choice antibiotics
Urinary tract infections (UTIs), after first-choice options haven't worked
Tuberculosis (TB) lung infection that is resistant (doesn't respond to) to other anti-TB antibiotics
Tuberculosis (TB) that is resistant (doesn't respond to) to first-choice anti-TB antibiotics (e.g., isoniazid or rifampin (Rifadin))
TB infection in people who can't take other anti-TB antibiotics
By signing up, I agree to GoodRx's Terms and Privacy Policy, and to receive marketing messages from GoodRx.
Centers for Disease Control and Prevention. (2016). Adverse events during treatment.
Centers for Disease Control and Prevention. (2022). About antimicrobial resistance.
Centers for Disease Control and Prevention. (2022). Drug resistant TB.
Centers for Disease Control and Prevention. (2023). Treatment for TB disease.
Dr. Reddy’s Laboratories, Inc. (2023). Cycloserine capsule [package insert]. DailyMed.
Kiran, C., et al. (2009). Understanding delusions. Industrial Psychiatry Journal.
Nahid, P., et al. (2019). Treatment of drug-resistant tuberculosis. An official ATS/CDC/ERS/IDSA Clinical Practice Guideline. American Journal of Respiratory and Critical Care Medicine.
Schacter, S. C. (n.d.). Alcohol as a seizure trigger. Epilepsy Foundation.
Schaumburg, H. H., et al. (2000). Cycloserine. Experimental and Clinical Neurotoxicology (Second Edition).
Tweed, C. D., et al. (2018). Liver toxicity associated with tuberculosis chemotherapy in the REMoxTB study. BioMed Central Medicine.
Research prescriptions and over-the-counter medications from A to Z, compare drug prices, and start saving.