Using drugs widely used to relieve nausea and vomiting are three times more likely to increase the risk of stroke, finds a study.

People with migraine, or undergoing chemotherapy or radiotherapy, are likely to suffer from nausea and vomiting and are known to use antidopaminergic antiemetics (ADAs) drugs. According to the study, published by The BMJ, the potential action of ADAs on blood flow to the brain could explain the higher risk. "The higher risk found for drugs crossing the blood-brain barrier suggests a potential central effect, possibly through an action on cerebral blood flow," the researchers said.

A team of researchers in France from Inserm and Bordeaux University (Bordeaux Population Health Centre) and Bordeaux CHU studied three ADAs - domperidone, metopimazine, and metoclopramide. All three were associated with an increased risk, especially in the first days of use, but the highest increase was found for metopimazine and metoclopramide.

Like antipsychotics, ADAs are antidopaminergic drugs - they work by blocking dopamine activity in the brain. Antipsychotics have been associated with an increased risk of ischaemic stroke, but whether this risk could extend to other antidopaminergics including ADAs is not known.

In the study, the team included 2,612 patients with a first ischaemic stroke between 2012 and 2016 and compared by age, sex, and stroke risk factors to a healthy control group of 21,859 randomly selected people who also received an ADA in the same time period.

Among patients with stroke, 1,250 received an ADA at least once in the risk period and 1,060 in the reference periods. Among the control group, 5,128 and 13,165 received an ADA at least once in the risk and reference periods, respectively.

After taking account of potentially influential factors, the researchers found that new users of ADA could be at a 3-fold increased risk of stroke shortly after treatment started. Further analyses by age, sex, and history of dementia showed similar results, with men at highest (a 3.59-fold increased) risk.

However, the team said "this is an observational study, and as such, can't establish cause". Nevertheless, they say their results show that the risk of ischaemic stroke appears to be associated with ADA use.