Can other drugs affect my Parkinson's medication?

Some prescription or over-the counter drugs can react badly with Parkinson’s medication. Here we look at what to avoid and what to check with a health professional.

If you have Parkinson’s then it’s likely you’ll have symptoms that don’t just affect movement. These are known as non-motor symptoms. They include things like anxiety, pain and constipation.

Treatments for these symptoms are normally the same types of drugs that anyone might use. For example, you may be prescribed a drug called Movicol for constipation.

But some medication can interfere with how Parkinson’s drugs work. This means that a particular drug can become weaker or stronger.

Below we list some examples of what we mean.

Herbal supplements

Herbal supplements are popular and many are safe to use. But some may affect your Parkinson’s drugs, such as St John’s Wort. This drug is often used for anxiety or low mood, but is not recommended for people with Parkinson’s.

It's made up of many elements which can interact with your Parkinson’s medication and cause side effects.

Iron tablets

You may take iron tablets if you have Parkinson’s. But iron tablets can affect how much Levodopa is absorbed in the body. You should aim to leave around 2 hours between taking iron supplements and Levodopa.

Cold and flu remedies

Decongestants are medicine that can provide short-term relief for a blocked or stuffy nose. These and cold remedies can stop your Parkinson’s medication working properly. This includes things like Lemsip. This is especially important to remember if you are taking selegiline, rasagiline and safinamide. They can also increase the risk of side effects.

Lady taking medication

Anti-sickness drugs

Parkinson’s medication can cause nausea and vomiting. Doctors will usually prescribe domperidone (Motilium) to prevent and treat this side effect. But some anti-sickness drugs will interact with Parkinson’s drugs. These include metoclopramide (Maxalon) and prochlorperazine (Stemetil).

Other anti-sickness drugs that are generally considered safe include cyclizine (Valoid) and 5-HT3 receptor antagonists like ondansetron.

Antipsychotic medication

Antipsychotic medication is used to treat hallucinations and delusions when someone experiences psychosis or schizophrenia. Antipsychotics and Parkinson’s medication can both affect the levels of dopamine in the brain. This means there needs to be a delicate balance so that symptoms of both conditions stay controlled.

Some can bring on Parkinson’s-like symptoms or react badly with Parkinson’s drugs.

Whoever prescribes you new medication should check what you’re already taking. And before you take something, it’s always good to double check with your specialist, Parkinson’s nurse or pharmacist whether there are any risks. This includes over-the-counter medication.