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What the label lists and what reports show

Cycloserine side effects

Cycloserine's FDA label lists its adverse reactions in its own words. FAERS holds 2,275 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is electrocardiogram qt prolonged (291 reports).

  • Generic listed

Check it at the source: the cycloserine FDA label on DailyMed (effective July 30, 2024, Dr. Reddys Laboratories, Inc.); the FDA FAERS public dashboard.

What does the label list?

From the label: adverse reactions

Most adverse reactions occurring during therapy with cycloserine involve the nervous system or are manifestations of drug hypersensitivity. The following side effects have been observed in patients receiving cycloserine: Nervous system symptoms (which appear to be related to higher dosages of the drug, i.e., more than 500 mg daily) • Convulsions • Drowsiness and somnolence • Headache • Tremor • Dysarthria • Vertigo • Confusion and disorientation with loss of memory • Psychoses, possibly with suicidal tendencies • Character changes • Hyperirritability • Aggression • Paresis • Hyperreflexia • Paresthesia • Major & minor (localized) clonic seizures • Coma Cardiovascular: Sudden development of congestive heart failure in patients receiving 1 to 1.5 g of cycloserine daily has been reported. …

Source: FDA drug label, ANDA060593 (Sanaluz), as published by Dr. Reddys Laboratories, Inc., effective July 30, 2024 (SPL set 8e7e2665-7a3d-3f54-9f92-5fe845f02ef9), via openFDA; the full label on DailyMed

What do FAERS reports show?

2,275 reports list cycloserine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 442 are coded as a death and 792 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 19 reactions below, 1 is named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.

Reports received each year

The 25 most reported reactions

  • Electrocardiogram Qt Prolonged291
  • Off Label Use (a use or a product term, not a reaction)280
  • Neuropathy Peripheral235
  • Anaemia (named in the label)222
  • Vomiting174
  • Nausea151
  • Drug Resistance120
  • Hepatotoxicity113
  • Tuberculosis (a use or a product term, not a reaction)96
  • Death (an outcome recorded in the report)85
  • Dyspnoea83
  • Asthenia80
  • Product Use In Unapproved Indication (a use or a product term, not a reaction)77
  • Drug Reaction With Eosinophilia And Systemic Symptoms72
  • Arthralgia70
  • Intentional Product Use Issue (a use or a product term, not a reaction)70
  • Decreased Appetite69
  • Hypokalaemia64
  • Pyrexia63
  • Gastrointestinal Disorder61
  • Treatment Failure (a use or a product term, not a reaction)61
  • Diarrhoea60
  • Drug-Induced Liver Injury60
  • Optic Neuritis56
  • Aspartate Aminotransferase Increased55

Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms

What next?

Cycloserine: the full record
label, generics, price, shortages, recalls
Side effects hub
the most reported medicines and reactions