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What the label lists and what reports show

Trihexyphenidyl side effects

Trihexyphenidyl's FDA label lists its adverse reactions in its own words. FAERS holds 995 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 nausea (52 reports).

  • Generic listed

Check it at the source: the trihexyphenidyl FDA label on DailyMed (effective October 25, 2019, Natco Pharma Limited); the FDA FAERS public dashboard.

What does the label list?

From the label: adverse reactions

Minor side effects, such as dryness of the mouth, blurred vision, dizziness, mild nausea or nervousness, will be experienced by 30 to 50 percent of all patients. These sensations, however, are much less troublesome with trihexyphenidyl HCl than with belladonna alkaloids and are usually less disturbing than unalleviated parkinsonism. Such reactions tend to become less pronounced, and even to disappear, as treatment continues. Even before these reactions have remitted spontaneously, they may often be controlled by careful adjustment of dosage form, amount of drug, or interval between doses. …

Source: FDA drug label, Natco Pharma Limited, effective October 25, 2019 (SPL set b7e4200c-feff-4537-aad1-cf9989fd8c14), via openFDA; the full label on DailyMed

What do FAERS reports show?

995 reports list trihexyphenidyl among the medicines taken, each a report of something that happened, not proof the medicine caused it; 177 are coded as a death and 513 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, 2 are 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

  • Off Label Use (a use or a product term, not a reaction)70
  • Drug Interaction (a use or a product term, not a reaction)63
  • Nausea (named in the label)52
  • Coma50
  • Fall48
  • Ischaemic Stroke42
  • Respiratory Distress41
  • Condition Aggravated (a use or a product term, not a reaction)38
  • Confusional State37
  • Respiratory Failure37
  • Hallucination (named in the label)36
  • Somnolence36
  • Pneumonia Aspiration35
  • Tremor34
  • Areflexia33
  • Cerebrovascular Accident33
  • Drug Ineffective (a use or a product term, not a reaction)33
  • Brain Scan Abnormal32
  • Drug Abuse32
  • Cerebral Artery Thrombosis31
  • Disease Recurrence31
  • Extrapyramidal Disorder (a use or a product term, not a reaction)31
  • Facial Paralysis30
  • Hemiplegia30
  • Product Use Issue (a use or a product term, not a reaction)30

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

What next?

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