MIAMI: Long-term use of an antihistamine known as diphenhydramine, which is in many popular sleeping aids, as well as medications for cold and allergies, can even cause irreparable harm.
One such study by Indiana University scientists showed they caused a reduction in brain functioning and smaller brain sizes.
Researchers found that those taking drugs which contained promethazine and diphenhydramine did not do as well on short-term memory tests than those who did not take the medications.