According to a study, people who take acid-reducing medications may be at a higher risk of migraines and other severe headaches than those who do not.

Acid-reducing medications include proton pump inhibitors like omeprazole and esomeprazole, histamine H2-receptor antagonists or H2 blockers like cimetidine and famotidine, and antacids.

The study does not prove that acid-reducing medicines cause migraines; it only indicates a relationship.

The findings of the study were published in the online issue of Neurology Clinical Practice, an official journal of the American Academy of Neurology.

Acid reflux is when stomach acid flows into the oesophagus, usually after a meal or when lying down. People with acid reflux may experience heartburn and ulcers. People with frequent acid reflux may develop gastroesophageal reflux disease, or GERD, which can lead to cancer of the oesophagus.

"Given the wide usage of acid-reducing drugs and these potential implications with migraine, these results warrant further investigation," said study author Margaret Slavin, PhD, RDN, of the University of Maryland in College Park.

"These drugs are often considered to be overprescribed, and new research has shown other risks tied to long-term use of proton pump inhibitors, such as an increased risk of dementia."

For the study, researchers looked at data on 11,818 people who provided information on the use of acid-reducing drugs and whether they had migraine or severe headaches in the past three months.

A total of 25 per cent of participants taking proton pump inhibitors had migraine or severe headaches, compared to 19 per cent of those who were not taking the drugs.

A total of 25 per cent of those taking H2 blockers had severe headaches, compared to 20% of those who were not taking those drugs. And 22 per cent of those taking antacid supplements had severe headaches, compared to 20 per cent of those not taking antacids.

When researchers adjusted for other factors that could affect the risk of migraine, such as age, sex and use of caffeine and alcohol, they found that people taking proton pump inhibitors were 70 per cent more likely to have migraine than people not taking proton pump inhibitors.

Those taking H2 blockers were 40 per cent more likely and those taking antacid supplements were 30 per cent more likely.

"It's important to note that many people do need acid-reducing medications to manage acid reflux or other conditions, and people with migraine or severe headache who are taking these drugs or supplements should talk with their doctors about whether they should continue," Slavin said.

Slavin noted that the study looked only at prescription drugs. Some of the drugs became available for over-the-counter use at non-prescription strength during the study period, but the use of these over-the-counter drugs was not included in this study.