Explains what antipsychotics are used for, how the medication works, possible side effects and information about withdrawal.
Anti-Parkinson’s drugs are mainly used to treat Parkinson's disease. They are not psychiatric drugs, which means they are not licensed to treat mental health problems.
But your doctor or psychiatrist may prescribe one of these drugs alongside an antipsychotic, to reduce certain side effects from the antipsychotic. These are known as neuromuscular side effects, as they affect your body’s neuromuscular system. The effects may also be known as Parkinsonism, as they are similar to some of the effects of Parkinson’s disease. These effects include:
There are three anti-Parkinson's drugs which may be prescribed alongside antipsychotics to reduce these symptoms:
These anti-Parkinson's drugs are sometimes known as antimuscarinics. Antimuscarinic is the term used for the group of effects that these drugs have on your body.
There are no significant differences between these three medications. But you may find that one of these drugs works better for you than others.
You should only be prescribed an anti-Parkinson's drug if you have developed Parkinsonism symptoms as a side effect of your antipsychotic, and
These drugs should never be prescribed to prevent side effects that you haven’t already experienced.
You should be especially careful about taking these drugs if you have:
You should avoid these drugs if you:
Trihexyphenidyl was first licensed before the current system of recording side effects was widely used. So estimates of how likely you are to experience these side effects are not available. The known side effects are listed below in alphabetical order.
Some patient information leaflets (PILs) for certain brands of trihexyphenidyl may list how common the side effects are for that specific brand. You can find the PIL in the box with your medication.
This information was published in September 2020. We will revise it in 2023.
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