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Trecator-SC Side Effects

Generic Name: ethionamide

Note: This page contains side effects data for the generic drug ethionamide. It is possible that some of the dosage forms included below may not apply to the brand name Trecator-SC.

For the Consumer

Applies to ethionamide: oral tablet

As well as its needed effects, ethionamide (the active ingredient contained in Trecator-SC) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking ethionamide, check with your doctor immediately:

Less common:
  • Clumsiness or unsteadiness
  • confusion
  • mental depression
  • numbness, tingling, burning, or pain in the hands and feet
  • yellow eyes or skin
  • Blindness or vision changes
  • blue-yellow color blindness
  • blurred vision or loss of vision, with or without eye pain
  • burning, crawling, itching, numbness, painful, prickling, "pins and needles", or tingling feelings
  • changes in menstrual periods
  • coldness
  • decreased sexual ability (in males)
  • decreased vision
  • difficulty in concentrating
  • dry, puffy skin
  • fast heartbeat
  • fever
  • hives, itching, or rash
  • hoarseness
  • increased hunger
  • increased sensitivity of the skin to sunlight
  • irritation
  • joint pain, stiffness, or swelling
  • redness or other discoloration of the skin
  • severe sunburn
  • shakiness
  • swelling of the eyelids, face, lips, hands, or feet
  • swelling of the front part of the neck
  • tightness in the chest
  • troubled breathing or swallowing
  • weakness in the hands or feet
  • weight gain
Incidence not known:
  • Chills
  • cold sweats
  • coma
  • cool, pale skin
  • dark urine
  • dizziness
  • general tiredness and weakness
  • headache
  • light-colored stools
  • nausea and vomiting
  • nightmares
  • seizures
  • slurred speech
  • unusual tiredness or weakness
  • upper right abdominal or stomach pain
  • yellow eyes and skin

Minor Side Effects

Some ethionamide side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common:
  • Abdominal or stomach pain
  • diarrhea
  • increased watering of the mouth
  • loss of appetite
  • metallic taste
  • swelling or inflammation of the mouth
  • weight loss
Incidence not known:
  • Blemishes on the skin
  • decreased interest in sexual intercourse
  • enlargement of the breasts (in males)
  • inability to have or keep an erection
  • loss in sexual ability, desire, drive, or performance
  • pimples

For Healthcare Professionals

Applies to ethionamide: oral tablet


Gastrointestinal side effects are the most common side effects of ethionamide (the active ingredient contained in Trecator-SC) and may be dose-related. They have included nausea, vomiting, diarrhea, abdominal pain excessive salivation, metallic taste, stomatitis, anorexia, and weight loss. Approximately one-half of patients cannot tolerate 1 gram as a single dose.[Ref]

Nervous system

Nervous system side effects have included psychotic disturbances, mental depression, drowsiness, dizziness, restlessness, headache, peripheral neuritis, and a pellagra-like syndrome. Concomitant pyridoxine has been recommended to prevent or relieve neurotoxic effects.[Ref]


Ocular side effects have rarely included optic neuritis, diplopia, and blurred vision.[Ref]


Hepatic side effects have included transient increases in serum bilirubin, SGOT, SGPT, and hepatitis with or without jaundice.[Ref]


Hypersensitivity reactions have rarely included rash, photosensitivity, thrombocytopenia, and purpura.[Ref]


Metabolic side effects have included hypoglycemia and hypothyroidism.[Ref]


Genitourinary side effects have included gynecomastia and impotence.[Ref]


Dermatologic side effects have included rash and acne.[Ref]


Hematologic side effects have included thrombocytopenia and purpura.[Ref]


Cardiovascular side effects have included postural hypotension.[Ref]


1. "Product Information. Trecator-SC (ethionamide)." Wyeth-Ayerst Laboratories, Philadelphia, PA.

2. McDonnell ME, Braverman LE, Bernardo J "Hypothyroidism due to ethionamide." N Engl J Med 352 (2005): 2757-9

3. Hussey HH "Editorial: Gynecomastia." JAMA 228 (1974): 1423

It is possible that some side effects of Trecator-SC may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.