Seromycin (Cycloserine) – Oral

What Is Seromycin?

Seromycin (cycloserine) is an orally administered prescription drug used as a second-line treatment (the second treatment used after the first treatment is not effective or tolerated) for pulmonary tuberculosis (TB) and urinary tract infections (UTIs).

Seromycin is approved for people 18 and older and is classified as an antitubercular agent.

Antitubercular agents are drugs specifically used to treat TB. Pulmonary TB is a disease that comes from infection with the bacteria Mycobacterium tuberculosis and impacts the lungs.

For further context, a UTI is an infection in any part of the urinary system. The urinary system includes the ureters, kidneys, urethra, and bladder.

Seromycin works by stopping bacteria from growing. However, it does not treat viral infections such as the common cold or flu. 

Cycloserine, the active ingredient in Seromycin, is available as an orally administered, generic drug.

This article will highlight Seromycin, a brand-name medication administered in the form of capsules to be taken orally (by mouth).

Drug Facts

Generic Name: Cycloserine
Brand Name: Seromycin
Drug Availability: Prescription
Administration Route: Oral
Therapeutic Classification: Antitubercular agent
Available Generically: Yes
Controlled Substance: N/A
Active Ingredient: Cycloserine
Dosage Form(s): Capsule

What Is Seromycin Used For? 

The Food and Drug Administration (FDA) has approved Seromycin for the treatment of pulmonary TB.

Seromycin is also FDA-approved to treat UTIs caused by certain types of bacteria. Seromycin is also a second-line treatment for UTIs.

Seromycin can also treat extrapulmonary TB, which is when the infection occurs in other organs such as the brain, spine, stomach, or kidneys.

In either type of TB, Seromycin is only used for bacteria shown to be susceptible to this drug. This means that lab tests show the drug will work against the bacteria.

Seromycin should be given with other medications for TB. It is not used as a sole treatment for TB.

How to Take Seromycin

Before taking Seromycin, read the information leaflet that comes with your prescription.

Ask your healthcare provider if you have any questions regarding the following:

  • Take Seromycin with or without food. 
  • Take Seromycin exactly as directed by your healthcare provider. 
  • Do not skip doses. 
  • Do not stop taking Seromycin before the full length of treatment is complete. 
  • Take Seromycin at evenly spaced intervals. For example, if you take Seromycin twice a day, take it every 12 hours.

Moreover, expect the following when taking Seromycin:

  • Your healthcare provider may instruct you to take cobalamin (vitamin B12) while you take Seromycin. This medication may also require supplementation with folic acid.
  • While taking Seromycin, your healthcare provider will monitor you closely. Keep all appointments and be sure to get all lab work that the healthcare provider orders.
  • Your healthcare provider will monitor your drug levels, kidney and liver function, and other blood work.


Seromycin should be stored at room temperature (68 to 77 degrees F), away from heat, direct light, and moisture. Do not store in a bathroom.

Keep Seromycin in its original labeled container and out of the reach of children and pets. Keep the bottle tightly closed when not in use.

How Long Does Seromycin Take to Work?

The time for Seromycin to work may vary depending on the severity of your condition and your ability to tolerate the medication.

Regardless, it is important to finish the full course of treatment even if you start to feel better. This prevents bacteria from returning and helps prevent antibiotic resistance.

Your healthcare provider will instruct you on how long you will have to take Seromycin, which may be for up to two years for TB.

What Are the Side Effects of Seromycin?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider. You may report side effects to the FDA at or 800-FDA-1088.

Common Side Effects

The most common side effects of Seromycin are:

Severe Side Effects

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency.

Serious side effects and their symptoms can include the following:

  • Anaphylaxis (hypersensitivity reactions): Symptoms can include rash, hives, swelling around the lips, tongue, and face, and difficulty breathing. These symptoms require emergency medical attention.
  • Seizures: Sudden and uncontrolled electrical activity in the brain
  • Psychosis: Symptoms can include hallucinations, agitation, and speaking incoherently. 
  • Suicidal ideation: Thoughts or ideas of suicide
  • Coma: A deep, prolonged loss of consciousness
  • Heart failure: Symptoms may include fatigue, shortness of breath, and swelling
  • Low red blood cell counts: Symptoms may include fatigue, shortness of breath, dizziness, weakness, fast heart rate, and headaches

Report Side Effects

Seromycin may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Seromycin Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For the oral dosage form (capsules):
    • For treatment of tuberculosis:
      • Adults and teenagers—250 milligrams (mg) two times a day to start. Your doctor may slowly increase your dose up to 250 mg three or four times a day. This medicine must be taken along with other medicines to treat tuberculosis.
      • Children—Use and dose must be determined by your doctor. Doses of 10 to 20 mg per kilogram (4.5 to 9.1 mg per pound) of body weight per day have been used. This medicine must be taken along with other medicines to treat tuberculosis.


Potential users should be aware of the following before beginning Seromycin:

Children: Seromycin is approved in adults only. It has not been studied for safety and efficacy in children.

Adults 65 and older: Clinical studies of Seromycin have not included enough people 65 and over to determine whether they respond differently from younger people. No differences in response were identified between older and younger people in other reported clinical data.

To be safe, dose selection for older individuals should start at the lower end of the dosing range. This is due to the general impaired liver, kidney, or heart function more likely in people of this age group.

Pregnancy: The effect of Seromycin in pregnancy is not known. Consult your healthcare provider if you are pregnant or planning to become pregnant.  

Breastfeeding: Seromycin should not be used by nursing people because it can cause serious side effects in the baby. 

People with kidney problems: Consult your healthcare provider if you have kidney problems. People with mild or moderate kidney problems may need a lower dose of Seromycin. People with severe kidney problems should not take Seromycin.  

Missed dose

If you miss a dose of Seromycin, take it as soon as you can.

If it is almost time for the next dose, skip the missed dose. Do not take two doses together. 

Overdose: What Happens If I Take Too Much Seromycin?

Symptoms of an overdose of Seromycin may include headache, feeling off-balance, confusion, drowsiness, numbness and tingling, slurred speech, psychosis, and extreme irritability.

With larger overdoses, muscle paralysis, seizures, and coma can occur.

It is important to avoid alcohol while taking Seromycin, as alcohol increases the risk of seizure in people who take Seromycin. 

What Happens If I Overdose on Seromycin

If you think you or someone else may have overdosed on Seromycin call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Seromycin, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check your progress at regular visits.

If your symptoms do not improve within 2 to 3 weeks, or if they become worse, check with your doctor.

If cycloserine causes you to feel very depressed or to have thoughts of suicide, check with your doctor immediately. Your doctor will probably want to change your medicine.

This medicine may cause some people to become dizzy, drowsy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert. If these reactions are especially bothersome, check with your doctor.

Some of cycloserine's side effects (for example, convulsions [seizures]) may be more likely to occur if you drink alcoholic beverages regularly while you are taking this medicine. Therefore, you should not drink alcoholic beverages while you are taking this medicine.

What Are Reasons I Shouldn’t Take Seromycin?

Seromycin is not appropriate for everyone. Some people should not take Seromycin.

You should not take Seromycin if you are allergic to cycloserine or any of the active ingredients in Seromycin.

Other people who should not take Seromycin include people with:

  • Epilepsy 
  • Depression 
  • Severe anxiety 
  • Psychosis 
  • Severe kidney problems
  • Excessive alcohol use 

Some people may be able to use Seromycin with caution and close monitoring by their healthcare provider. These include people with:

  • Mild or moderate kidney problems
  • Liver problems
  • Anemia (low red blood cell counts) 

Before taking Seromycin, tell your healthcare provider about your medical history and current medical conditions. Tell your healthcare provider if you have a substance use disorder. 

Interactions: What Other Medications Should I Avoid? 

Certain medications or substances should be avoided in combination with Seromycin, including:

Before taking Seromycin, tell your healthcare provider about all the medications you take, including prescription, over-the-counter (OTC), vitamins, and supplements.

What Medications Are Similar?

According to the Centers for Disease Control and Prevention (CDC), the first-line drugs (first drugs recommended) for TB are used in combination with one another and include:

  • Myambutol (ethambutol)
  • Isoniazid
  • Pyrazinamide
  • Rifadin (rifampin)

There are various regimens, each with an intensive phase of eight weeks (two months), followed by a continuation phase of four to seven months, for a total of six to nine months of treatment. 

Second-line drugs for TB are also prescribed in combination and include:

  • Group A: Levaquin (levofloxacin), Sirturo (bedaquiline), and Zyvox (linezolid)
  • Group B: Lamprene (clofazimine), and cycloserine or terizidone
  • Group C: Myambutol (ethambutol), delamanid, pyrazinamide, imipenem-cilastatin or meropenem, amikacin, ethionamide or prothionamide, and p-aminosalicylic acid

The above is a list of drugs also prescribed for TB. It is not a list of drugs recommended to take with Seromycin. Ask your healthcare provider if you have questions.

Frequently Asked Questions

  • What is Seromycin used for?

    Seromycin is used as a second-line treatment for TB that affects the lungs or other organs. Seromycin should be used in combination with other medications for TB. 

    Seromycin can also be used in certain types of UTIs as a second-line treatment after another treatment has failed.

  • How does Seromycin work?

    Seromycin works by stopping bacteria from growing.

  • What drugs should not be taken with Seromycin?

    Alcohol should never be consumed when taking Seromycin because alcohol and Seromycin together can increase seizure risk.

    Other drugs that interact with Seromycin include isoniazid, ethionamide, and BCG live intravesical. 

  • How long does it take for Seromycin to work?

    The time for Seromycin to work varies. However, even if you start feeling better, it is important to finish the full course of treatment to make sure the bacteria are eliminated and to help prevent antibiotic resistance.

    You may need to take Seromycin for up to two years for TB.

  • What are the side effects of Seromycin?

    The most common side effects of Seromycin are sleepiness, headache, tremor, slurred speech, vertigo, memory problems, confusion, behavior changes, numbness and tingling, overactive reflexes, and rash.

    Symptoms of an allergic reaction include hives, difficulty breathing, and swelling around the face, lips, tongue, or throat. These symptoms require emergency medical attention.

How Can I Stay Healthy While Taking Seromycin

Treating TB can be a very long and complicated process, requiring you to remember to take many medications. It can help to use a pill organizer to keep track of the dosing schedule.

Order medication refills at least three to five days in advance. This allows the pharmacy plenty of time in case they need to order the medication (or any of the other medications you will be taking along with Seromycin) or call the healthcare provider for refills if needed.

Ordering your medicine early ensures that you will not have any interruptions in your dosing schedule. 

Avoid alcohol while taking Seromycin. Alcohol in combination with Seromycin can increase the risk of seizures.

In addition to avoiding alcohol in the form of beverages, be on the lookout for hidden sources of alcohol in foods, such as in sauces, or other products such as mouthwash or cough syrup.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. DailyMed. Label: Seromycin- cycloserine capsule.

  2. Centers for Disease Control and Prevention. Basic TB facts.

  3. Centers for Disease Control and Prevention. Urinary tract infection.

  4. DailyMed. Label: cycloserine capsule.

  5. Merck Manual - Professional Version. Extrapulmonary tuberculosis (TB).

  6. Centers for Disease Control and Prevention. Treatment regimens for latent TB Infection.

  7. Nahid P, Mase SR, Migliori GB, et al. Treatment of drug-resistant tuberculosis. An official ATS/CDC/ERS/IDSA clinical practice guideline [published correction appears in Am J Respir Crit Care Med. 2020;15;201(4):500-501]Am J Respir Crit Care Med. 2019;200(10):e93-e142. doi:10.1164/rccm.201909-1874ST

By Karen Berger, PharmD
Karen Berger, PharmD, is a community pharmacist and medical writer/reviewer.