This guide will help you answer 4.2 Describe the common side-effects of medication for Parkinson’s disease.
Parkinson’s disease affects movement, muscle control, and coordination. There is no cure, but medication can help manage symptoms. Each type of medication works in a different way, usually by replacing or boosting dopamine, which is low in the brain of someone with Parkinson’s.
While these medicines can make a big difference, they can also cause side-effects. These effects can vary between individuals. Some side-effects appear soon after starting treatment, while others may develop over time.
Workers in health and social care need to recognise these side-effects. This helps to support the person and report concerns to healthcare professionals.
Why Side-Effects Happen
Medicines for Parkinson’s affect the brain’s chemistry. By changing dopamine levels, they also influence other brain chemicals. This can affect mood, thinking, and body functions. Some medicines may influence the digestive system, blood pressure, or movement control in unexpected ways. Everyone reacts differently, so not all people will have the same side-effects or severity.
Main Types of Parkinson’s Medication
Most side-effects depend on the type of drug used. Common groups of medication for Parkinson’s include:
- Levodopa – changes into dopamine in the brain
- Dopamine agonists – copy the action of dopamine
- MAO-B inhibitors – slow the breakdown of brain dopamine
- COMT inhibitors – prolong the effects of levodopa
- Amantadine – helps with symptoms such as tremor or muscle stiffness
- Anticholinergics – reduce tremors by blocking certain nerve signals
Common Side-Effects of Levodopa
Levodopa is the most widely used medication for Parkinson’s. It is often combined with another drug (such as carbidopa or benserazide) to help it work better and reduce nausea.
Typical side-effects include:
- Nausea and vomiting – feeling sick or being sick, especially early in treatment
- Loss of appetite – eating less or feeling full quickly
- Low blood pressure when standing (postural hypotension) – dizziness or light-headedness when standing up
- Involuntary movements (dyskinesia) – jerky or writhing movements that the person cannot control
- Confusion or hallucinations – seeing, hearing, or sensing things that are not there
- Sleepiness – some people feel unusually tired during the day
Levodopa can also cause fluctuations in symptom control over time, known as “on-off” effects. The person may feel good during “on” times but slow and stiff during “off” times before the next dose.
Common Side-Effects of Dopamine Agonists
Dopamine agonists are one group of Parkinson’s medicines. See the NHS Parkinson’s disease treatment page for the medicines currently used. They mimic dopamine effects in the brain and tend to be used alone in early stages or alongside levodopa later.
Side-effects can include:
- Sleep attacks – sudden, unexpected sleep without warning
- Severe drowsiness – overwhelming tiredness even after rest
- Nausea – feeling or being sick
- Confusion or hallucinations – especially in older people
- Impulsive behaviours – uncontrollable urges such as gambling, overspending, binge eating, or hypersexuality. Staff must watch for changes in personality or habits and report them quickly
- Low blood pressure when standing – as with levodopa
Sleep attacks and impulse control disorders are particularly important for care workers to recognise because the person may not link these problems to the medication.
Common Side-Effects of MAO-B Inhibitors
MAO-B inhibitors include selegiline, rasagiline, and safinamide. They block the enzyme monoamine oxidase B, which breaks down dopamine. This helps keep dopamine levels higher for longer.
Side-effects may include:
- Nausea or stomach discomfort – often mild but can lead to reduced food intake
- Dry mouth – uncomfortable and can affect taste and dental health
- Headaches – recurring or persistent
- Insomnia – difficulty sleeping, especially if taken late in the day
- Dizziness – often mild but can increase fall risk
- Confusion or hallucinations – more common in older adults
Some Parkinson’s medicines can interact with other medicines. Staff should not add, stop or swap any medicine or supplement without asking the prescriber or pharmacist. Check the latest advice on the NHS Parkinson’s disease treatment page.
Common Side-Effects of COMT Inhibitors
COMT inhibitors include entacapone and tolcapone. They block an enzyme that breaks down levodopa, allowing the drug to last longer in the body. They are usually taken alongside levodopa.
Common side-effects:
- Diarrhoea – tell the prescriber or specialist team, who will decide what to do; never stop the medicine without advice
- Nausea – feeling sick
- Worsening of involuntary movements – dyskinesia may increase because levodopa levels are more constant
- Abdominal pain – cramping or discomfort
- Confusion or hallucinations
Common Side-Effects of Amantadine
Amantadine is one of the medicines sometimes used to help with Parkinson’s symptoms. See Parkinson’s UK drug treatments.
Possible side-effects:
- Swelling in the legs and ankles – water retention
- Dizziness and light-headedness
- Dry mouth – can lead to swallowing problems or tooth decay
- Confusion and hallucinations – often in older adults or those with memory problems
- Anxiety or restlessness – mood changes
Common Side-Effects of Anticholinergics
Anticholinergics are another group of Parkinson’s medicines, prescribed for each person by the specialist team. See Parkinson’s UK drug treatments.
Side-effects include:
- Dry mouth – can be severe, causing chewing and swallowing problems
- Blurred vision – affects reading and daily activities
- Constipation – uncomfortable and can cause distress
- Difficulty passing urine – tell the GP or Parkinson’s nurse promptly
- Confusion or memory problems – especially worrying in older people
- Drowsiness – can affect alertness
Mental and Behavioural Side-Effects
Across all Parkinson’s medications, some side-effects affect thinking, mood, or behaviour. These can include:
- Hallucinations – seeing or hearing things not present
- Delusions – false beliefs that may cause distress
- Depression – severe low mood, loss of interest in activities
- Anxiety – constant worry or restlessness
- Impulse control disorders – sudden loss of control over urges, such as gambling or spending
These effects can make daily living difficult. They can also cause risk to personal safety or financial harm. Support workers must monitor changes closely and record them so they can be addressed promptly.
Physical Side-Effects Across Different Drugs
Some physical problems occur with several kinds of Parkinson’s medication.
Common shared side-effects include:
- Low blood pressure when standing – can lead to falls
- Nausea and vomiting
- Constipation
- Sleep problems
- Skin changes – rashes, itching, or colour changes
- Weight changes – gain from fluid retention or loss from reduced appetite
Monitoring and Reporting Side-Effects
In care settings, it is important to:
- Watch for signs of new or worsening symptoms
- Keep accurate written records in care notes
- Inform the GP, Parkinson’s nurse, or pharmacist about concerns
- Support the person emotionally if side-effects are distressing
- Provide reassurance and encourage open discussion about how the medication is affecting daily life
Care workers should never stop or change medication without medical advice. Sudden changes can be dangerous. Only doctors or specialist nurses should alter treatment doses.
Practical Tips for Supporting Someone with Side-Effects
- Encourage slow position changes to prevent dizziness when standing
- Make sure living areas are safe if the person has poor balance or sudden sleep attacks
- Respect privacy and dignity when discussing sensitive side-effects such as impulse control problems
- Help with dental care if dry mouth is an issue
- Tell the GP or Parkinson’s nurse about constipation, as they can advise on managing it
Final Thoughts
Medicines for Parkinson’s disease can transform quality of life. They can reduce tremors, stiffness, and movement difficulties. At the same time, they can trigger a range of side-effects, both physical and psychological.
Support workers and carers play a vital role in noticing these effects early. This allows doctors to adjust treatment before problems become severe. Careful observation, good record-keeping, and open communication help keep the person safe and comfortable.
Being aware of the common side-effects of Parkinson’s medication makes care more effective. It helps each person get the full benefit of their treatment with the least discomfort. This improves both safety and quality of life.