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Trihexyphenidyl Side Effects

Medically reviewed by Drugs.com. Last updated on Dec 8, 2023.

Applies to trihexyphenidyl: oral elixir, oral tablet.

Common side effects of trihexyphenidyl

Some side effects of trihexyphenidyl 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

  • dizziness
  • mild nausea
  • nervousness

Incidence not known

  • drowsiness
  • weakness

Serious side effects of trihexyphenidyl

Along with its needed effects, trihexyphenidyl 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 while taking trihexyphenidyl:

Rare

  • abdominal or stomach cramps or pain
  • bloating
  • constipation
  • delusions of persecution, mistrust, suspiciousness, or combativeness
  • excessive dryness of the mouth
  • false beliefs that cannot be changed by facts
  • loss of appetite
  • nausea or vomiting
  • seeing, hearing, or feeling things that are not there
  • skin rash
  • stomach pain
  • swollen, painful, or tender lymph glands on the side of the face or neck

Incidence not known

  • anxiety
  • blurred vision
  • change in vision
  • decrease in frequency of urination
  • decrease in urine volume
  • difficult urination
  • difficulty in passing urine (dribbling)
  • disturbed behavior
  • dry mouth
  • enlarged pupils
  • eye pain
  • fast, pounding, or irregular heartbeat or pulse
  • hyperventilation
  • irritability
  • loss of vision
  • mental confusion
  • nervousness
  • painful urination
  • restlessness
  • shaking
  • shortness of breath
  • trouble sleeping

For Healthcare Professionals

Applies to trihexyphenidyl: oral elixir, oral tablet.

General

The most commonly reported adverse reactions have included dry mouth, blurred vision, dizziness, nausea, and nervousness.[Ref]

Gastrointestinal

Isolated cases of suppurative parotitis secondary to excessive dryness of the mouth have been reported.[Ref]

Nervous system

Psychiatric

Toxic psychosis, when present, tends to occur quickly, generally within several days to a week of initiating therapy or within hours after an acute overdose. However, occasionally the onset may be delayed by months. Symptoms generally resolve spontaneously within a few days after the discontinuation of medication.

Psychiatric deterioration and psychotic flare-ups have also been reported following withdrawal of therapy. Symptoms include delusions, hallucinations, aggression or violent behavior, and suicidal tendencies. In high dosages, it may produce euphorigenic effects. For this reason, it can be a drug of abuse.[Ref]

Ocular

Cardiovascular

Genitourinary

Other

Hypersensitivity

Dermatologic

References

1. (2001) "Product Information. Artane (trihexyphenidyl)." Lederle Laboratories

2. Baker LA, Cheng LY, Amara IB (1983) "The withdrawal of benztropine mesylate in chronic schizophrenic patients." Br J Psychiatry, 143, p. 584-90

3. Kalman T, Warner GM (1978) "Protracted vomiting following abrupt cessation of psychotropics: a case report." Can Psychiatr Assoc J, 23, p. 163-5

4. McEvoy JP, McCue M, Spring B, Mohs RC, Lavori PW, Farr RM (1987) "Effects of amantadine and trihexyphenidyl on memory in elderly normal volunteers." Am J Psychiatry, 144, p. 573-7

5. Warne RW, Gubbay SS (1979) "Choreiform movements induced by anticholinergic therapy." Med J Aust, 1, p. 465

6. Birket-Smith E (1974) "Abnormal involuntary movements induced by anticholinergic therapy." Acta Neurol Scand, 50, p. 801-11

7. Koller WC (1984) "Disturbance of recent memory function in parkinsonian patients on anticholinergic therapy." Cortex, 20, p. 307-11

8. Nomoto M, Thompson PD, Sheehy MP, Quinn NP, Marsden CD (1987) "Anticholinergic-induced chorea in the treatment of focal dystonia." Mov Disord, 2, p. 53-6

9. Hauser RA, Olanow CW (1993) "Orobuccal dyskinesia associated with trihexyphenidyl therapy in a patient with Parkinson's disease." Mov Disord, 8, p. 512-4

10. el-Yousef MK, Janowsky D, Davis JM, Sekerke HJ (1973) "Reversal of antiparkinsonian drug toxicity by physostigmine: a controlled study." Am J Psychiatry, 130, p. 141-5

11. Glassman JN, Darko D, Gillin JC (1986) "Medication-induced somnambulism in a patient with schizoaffective disorder." J Clin Psychiatry, 47, p. 523-4

12. West RR, Newgreen DB (1979) "Choreiform movements induced by anticholinergic therapy." Med J Aust, 2, p. 87-8

13. Moreau A, Jones BD, Banno V (1986) "Chronic central anticholinergic toxicity in manic depressive illness mimicking dementia." Can J Psychiatry, 31, p. 339-41

14. Yassa R (1985) "Antiparkinsonian medication withdrawal in the treatment of tardive dyskinesia: a report of three cases." Can J Psychiatry, 30, p. 440-2

15. McEvoy JP, Freter S (1989) "The dose-response relationship for memory impairment by anticholinergic drugs." Compr Psychiatry, 30, p. 135-8

16. Burnett GB, Prange AJ Jr, Wilson IC, Jolliff LA, Creese IC, Synder SH (1980) "Adverse effects of anticholinergic antiparkinsonian drugs in tardive dyskinesia. An investigation of mechanism." Neuropsychobiology, 6, p. 109-20

17. Kiloh LG, Smith JS, Williams SE (1973) "Antiparkinson drugs as causal agents in tardive dykinesia." Med J Aust, 2, p. 591-3

18. McEvoy JP (1987) "A double-blind crossover comparison of antiparkinson drug therapy: amantadine versus anticholinergics in 90 normal volunteers, with an emphasis on differential effects on memory function." J Clin Psychiatry, 48(9 suppl, p. 20-3

19. Stephens DA (1967) "Psychotoxic effects of benzhexol hydrochloride (Artane)." Br J Psychiatry, 113, p. 213-8

20. Warnes H (1967) "Toxic psychosis due to antiparkinsonian drugs." Can Psychiatr Assoc J, 12, p. 323-6

21. Trend P, Trimble M, Wessely S (1989) "Schizophrenic psychosis associated with benzhexol (artane) therapy." J Neurol Neurosurg Psychiatry, 52, p. 1115

22. Wilcox JA (1983) "Psychoactive properties of benztropine and trihexyphenidyl." J Psychoactive Drugs, 15, p. 319-21

23. Laski E, Taleporos E (1977) "Anticholinergic psychosis in a bilingual: a case study." Am J Psychiatry, 134, p. 1038-40

24. Friedman Z, Neumann E (1972) "Benzhexol-induced blindness in Parkinson's disease." Br Med J, 1, p. 605

25. Blumensohn R, Razoni G, Shalev A, Munitz H (1986) "Bradycardia due to trihexyphenidyl hydrochloride." Drug Intell Clin Pharm, 20, p. 786-7

26. Johnson AL, Hollister LE, Berger PA (1981) "The anticholinergic intoxication syndrome: diagnosis and treatment." J Clin Psychiatry, 42, p. 313-7

27. Hussey HH (1975) "Physostigmine: value in treatment of central toxic effects of anti-cholinergic drugs." JAMA, 231, p. 1066

28. Kulik AV, Wilbur R (1982) "Delirium and stereotypy from anticholinergic antiparkinson drugs." Prog Neuropsychopharmacol Biol Psychiatry, 6, p. 75-82

Further information

Trihexyphenidyl side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

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