Slowness, stiffness and tremor caused by medications
Drug-induced parkinsonism is a condition that causes symptoms like Parkinson’s disease, but which develops as a side effect of certain medications rather than from an underlying brain disease.
Drug-induced parkinsonism is one of the most common reversible causes of parkinsonism, and symptoms usually improve, often fully, after the responsible medication is stopped or reduced. This can reassure patients and caregivers that recovery is often possible.
What is drug-induced parkinsonism?
Drug-induced parkinsonism can occur when a medication blocks or reduces the effect of dopamine, a chemical messenger the brain relies on for smooth, controlled movement. Because a loss of dopamine-producing brain cells causes Parkinson’s disease itself, blocking dopamine’s effect with a medication can produce a very similar pattern of symptoms, even though the brain cells themselves are not damaged.
Certain groups of medications are more commonly associated with this condition, including:
- antipsychotic medications – particularly older (‘typical’) antipsychotics, though some newer ones can also cause it
- anti-nausea medications – such as metoclopramide and prochlorperazine, which are commonly used but can affect dopamine signalling
- other medications – including antidepressants, some medications used for dizziness or certain calcium channel blockers.
Over time, drug-induced parkinsonism typically affects:
- movement speed and stiffness, similar to typical Parkinson’s disease
- tremor, which may be present but is sometimes less prominent or different in pattern than Parkinson’s tremor
- walking and balance, in more pronounced cases
- facial expression and speech, in some cases.
What increases the risk of drug-induced parkinsonism?
Because this condition is triggered by medication rather than an underlying brain disease, its risk factors relate mainly to medication exposure and individual sensitivity.
Factors that can’t be changed include:
- age – older adults appear more sensitive to the dopamine-blocking effects of certain medications, increasing their risk of developing symptoms
- sex – some studies suggest women may be more susceptible than men, though this isn’t fully established
- underlying, undiagnosed Parkinson’s disease – in some people, a dopamine-blocking medication can unmask early, previously unnoticed Parkinson’s disease, making symptoms more prominent or slower to resolve after the medication is stopped.
Factors that may be modifiable, meaning they relate to medication use and can potentially be adjusted with medical guidance, include:
- type and dose of medication – higher doses and more potent dopamine-blocking medications carry a greater risk
- duration of use – longer-term use of the responsible medication increases both the likelihood of developing symptoms and the time needed for symptoms to resolve after stopping
- use of multiple dopamine-blocking medications together – combining more than one such medication can increase risk.
Because drug-induced parkinsonism is closely tied to specific medications, the most effective way to reduce risk is for prescribers to:
- use the lowest effective dose for the shortest appropriate time
- consider alternative medications where possible, particularly in older adults.
Common patient questions
No. The symptoms can look very similar to Parkinson’s disease. Still, drug-induced parkinsonism may be caused by a medication temporarily blocking dopamine’s effects, rather than by ongoing loss of dopamine-producing brain cells.
Recognising this similarity can help patients understand that the condition is often reversible and distinct from Parkinson’s disease, which is more persistent and progressive.
Often, yes, though it can take weeks to months after stopping or reducing the responsible medication for symptoms to resolve fully. In some cases, particularly with long-term use, recovery can be slower or incomplete, and the medication can have unmasked early, underlying Parkinson’s disease in some people.
No. It is caused by medication exposure rather than genetic or inherited factors, though some people may be more sensitive to these medication effects than others.
The main treatment involves working with a doctor to identify and reduce or stop the medication causing symptoms. Supportive care may help manage symptoms while they improve, and further assessment might be needed if symptoms persist.