Do hay fever tablets raise risk of dementia?

hay fever tablets dementia

Alarming headlines in several UK newspapers and news websites this week (27 January 2015) claiming a US study concluded common hay fever tablets available over the counter raise the risk of developing dementia and Alzheimer’s disease.

While there are significant findings in the study, the news reporting was not entirely accurate according to NHS ‘Behind the headlines’ (page now removed). Much of the reporting failed to highlight the study focus was on prescribed medicine for over 65s only; some brand name drugs contain different ingredients in the US to the UK; and other limitations of the study findings.

Although some of the drugs can be bought over the counter, the study only included prescribed medicines which have an anticholinergic effect, including some antihistamines, antidepressants and drugs for an overactive bladder, and concludes those over 65s taking the highest levels of anticholinergic prescribed medicines were at a higher risk of developing dementia compared with those not taking any.

Some of the medicine brands also contain different ingredients in the UK than the US: Benadryl and Piriteze do not contain ingredients identified in the study as causes of concern.

The main statistically significant finding was in a group [over 65 years] taking the equivalent of any of the following medications daily for more than three years:

  • xybutynin chloride, 5mg
  • chlorpheniramine maleate, 4mg
  • olanzapine, 2.5mg
  • meclizine hydrochloride, 25mg
  • doxepin hydrochloride, 10mg

These are not unrealistic doses of medicine, so the results may be applicable to a significant proportion of older adults.

NHS: Media dementia scare over hay fever and sleep drugs

If you have been prescribed these medicines, you must speak to a doctor first before you stop taking them. It may be more harmful for you to stop, and there is no evidence to say reducing the amount of anticholinergic medicines will reduce the risk of dementia to normal.

Dr Fox provides newer non-sedative antihistamines for hay fever which are of a different type to those that raise concern in the study.

Excerpt from The Daily Mail: the manufacturer of Benadryl, Johnson & Johnson, have confirmed none of their UK products contain the active ingredient diphenhydramine.