Anticholinergics: Medicines involved

Last updated: August 08, 2019

A whole range of medicines potentially have anticholinergic side effects and it is not possible to list all of them here. A review in BMC Geriatrics has a very extensive table if you'd like something more comprehensive and there's an alphabetical list on the ACB Calculator site. Note that sources can disagree about the strength of anticholinergic action of some medicines.

However, many medicines have only weak effects and/or are rarely used in practice. The commonly-prescribed medicines with more explicit anticholinergic actions include:

Analgesics for neuropathic pain

  • Tricyclic antidepressants such as amitriptlyine, imipramine and nortriptyline are relatively potent anticholinergics, but carbamazepine has some action too.

Antidepressants

  • Tricyclic antidepressants such as amitriptlyine, imipramine and nortriptyline are the worst offenders. SSRIs generally have only minor anticholinergic actions, but paroxetine is considered the most potent.

Antiemetics and vertigo

  • Prochlorperazine, cyclizine, promethazine and hyoscine are examples with notable anticholinergic actions.

Antihistamines

  • The older generation ones like chlorphenamine (Piriton), hydroxyzine, promethazine (Phenergan), and diphenhydramine have a stronger anticholinergic action than newer ones like fexofenadine. Older antihistamines with anticholinergic actions can be 'hidden' ingredients in over-the-counter medicines for insomnia (e.g. Nytol) and colds (e.g. Benylin).

Antipsychotics

  • Many of these have at least some anticholinergic action, although often it is the older agents like chlorpromazine and clozapine that are more potent. However, some newer agents like olanzapine have anticholinergic activity.

'Classical' anticholinergics

  • Hyoscine and atropine are used for many different indications and in various dosage forms, but are particularly potent anticholinergic medicines.

Gastrointestinal medicines

  • Medicines for gastrointestinal spasm such as dicycloverine (dicyclomine), hyoscine, and propantheline have anticholinergic actions. 

Parkinsonism medicines (and extrapyramidal symptoms)

  • Medicines to control movement disorders of this kind include procyclidine, orphenadrine, and trihexyphenidyl. Mental health patients with drug-induced Parkinsonism may be particularly taking these medicines. 

Respiratory medicines

  • Bronchodilators such as ipratropium and tiotropium are anticholinergic drugs. Their side effect potential is much less than the other medicines cited here, mainly because they are given by inhalation.

Urology medicines

  • Medicines for urinary incontinence and related symptoms such as oxybutynin, solifenacin, tolterodine, trospium, and propiverine.

Even this incomplete summary is quite a lot of information to keep in your head. Later in this tutorial, we've provided an A4-sized poster you can print off and keep available for reference.


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