Procyclidine

Key facts

• Procyclidine (brand name Kemadrin) is an anticholinergic that blocks acetylcholine to relax overactive muscle tone.
• It treats Parkinson's disease tremor and stiffness, and movement side effects caused by antipsychotic medicines; an injection can reverse a sudden dystonic reaction, such as a twisted neck or eyes rolling back, within minutes.
• Procyclidine must be avoided in untreated angle-closure glaucoma and urinary retention: its anticholinergic action can raise eye pressure dangerously or make it impossible to pass urine.
• Seek urgent care for eye pain with blurred vision, inability to urinate, or new confusion or hallucinations.

What procyclidine treats

Procyclidine treats the tremor, rigidity, and excess saliva of Parkinson's disease, and drug-induced extrapyramidal symptoms, the stiffness, tremor, and abnormal muscle spasms caused by antipsychotics and some other dopamine-blocking medicines. An injectable form is used as emergency treatment for acute dystonic reactions.

How procyclidine works

Procyclidine blocks muscarinic acetylcholine receptors in the brain's movement-control circuits. This restores balance with dopamine signaling, which is reduced in Parkinson's disease or blocked by antipsychotic drugs, easing tremor, rigidity, and involuntary muscle contractions.

Before you take it

• Avoid procyclidine if you have untreated angle-closure glaucoma, urinary retention, or bowel obstruction.
• Tell your prescriber about an enlarged prostate, myasthenia gravis, or a heart rhythm problem, since anticholinergic effects can worsen these conditions.
• Avoid combining procyclidine with alcohol or other anticholinergic drugs, such as some antihistamines or antidepressants, since dry mouth, confusion, and constipation add up.
• Older adults are more prone to confusion and should be monitored closely.

Side effects

Common effects include dry mouth, blurred vision, constipation, dizziness, and difficulty passing urine.

Stop and seek urgent medical care for any of these:

• Eye pain with vision loss (possible acute glaucoma).
• Inability to urinate.
• A fast heartbeat.
• Severe confusion or hallucinations.

Safety essentials

• Do not use procyclidine if you have untreated angle-closure glaucoma or urinary retention: it can turn either into a medical emergency.
• Combining it with alcohol or other anticholinergic medicines increases confusion, overheating risk, and constipation, particularly in older adults.
• Procyclidine has a recognized potential for misuse because of its mood-altering effects at high doses; take it only as prescribed.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.