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  • Generic
  • Brand
  • Anticholinergic agents
  • amantadine
  • Symmetrel
  • benztropine
  • Cogentin
  • diphenhydramine
  • Benadryl
  • trihexyphenidyl
  • Artane

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Antiparkinsonian (anticholinergic) medications are used to control the side effects associated with antipsychotic medications. They are called antiparkinsonian because the neurological side effects of antipsychotic medications are similar to the symptoms of Parkinson’s disease (i.e., tremors, stiff or rigid muscles, poor balance, and a distinctive unsteady walk). The antiparkinsonian medications listed in this section are only those used in the management of the side effects of antipsychotic medications. There are other medications used to treat primary Parkinson’s disease that are not discussed in this section because those medications are currently not used for the management of side effects related to antipsychotics. If you would like more information on Parkinson’s disease talk with your doctor or pharmacist.


All medications have specific doses and frequencies. The physician will specify the exact amount of medication and when it should be taken. This information is on the prescription bottle. These medications have very specific doses and taking too much can be harmful. A doctor must be consulted in order to safely change the dose in response to side effects of the antipsychotic medications.

  • Constipation
  • Dizziness
  • Dry mouth
  • Heart failure
  • Irritability
  • Light-headedness
  • Stomach upset
  • Tiredness

Report immediately any overdose or changes in heart rate and/or rhythm to the doctor.


Despite their utility, these medications can be abused by some persons with severe mental illness who require neuroleptics. Survey research has found that many abusers of antiparkinsonians used these medications “to get high, to increase pleasure, to decrease depression, to increase energy and to relax” (Buhrich et al. 2000, p. 929). The survey also found that the misuse of other drugs accompanied the misuse of antiparkinsonian medications. Consequently, in the context of co-occurring mental health and substance use disorders, providers and consumers need to be aware of and openly communicate about the abuse potential of these medications.

  • Doctors and pharmacists should be told about all medications being taken and dosage, including over-the-counter preparations, vitamins, minerals, and herbal supplements (i.e., St. John’s wort, echinacea, ginkgo, and ginseng).
  • People taking antiparkinsonian medications should not increase their dose unless this has been checked with their physician and a change is ordered.

The risk of birth defects associated with benztropine, trihexyphenidyl, and diphenhydramine is not clear, although there is some evidence to suggest that amantadine may produce a deformed baby (Mortola 1989). For all women of childbearing age who may be or think they may be pregnant, the physician should discuss the safety of this medication before starting, continuing, or discontinuing medication treatment. Substance abuse counselors may have a role in encouraging this discussion by suggesting their clients talk with the prescribing physician.

Addiction Technology Transfer Center Network