Anticholinergics are medications that block the action of the neurotransmitter acetylcholine. Acetylcholine controls many bodily functions not under voluntarily control, including sweating, balancing, pupil dilation, contraction of bladder muscles, digestion and salivation. Many common medications have anticholinergic side effects. Many of the drugs used for allergies, motion sickness, coughs and colds, nausea, overactive bladder, diarrhea and overactive bladder have anticholinergic effects. While anticholinergic medications have benefits, they also have a variety of side effects.
Dry Mouth, Nose and Throat
Anticholinergic drugs dry secretions in the mouth, nose, throat and lungs. These effects can be beneficial when they are the desired result of medications for treating coughs and colds, but they are adverse effects when they result from medications used for other purposes. Dry mouth is a very common effect, and if persistent can cause ulceration of the gums, tooth decay and fungal infections.
Anticholinergics slow digestion by affecting the ability of the intestines to contract. They also cause decreased secretions to provide moisture to intestinal contents. Constipation is a common side effect that results.
Drowsiness is a common side effect. Over-the-counter sleep medications such as Tylenol PM, Excedrin PM and Unisom contain anticholinergics to induce sleep, but sleepiness can occur from any medicine that contains an anticholinergic.
Flushing and Overheating
According to MayoClinic.com, anticholinergic medications reduce sweating and cause body temperature to increase. Extra care should be used to avoid overheating during exercise and in hot weather in order to avoid a heat stroke. Hot baths and saunas should be avoided because dizziness or fainting can result.
Confusion and Memory Loss
The elderly suffer increased risk of confusion and memory loss while taking anticholinergic drugs. This risk is made worse due to the common practice of prescribing multiple medications that may have anticholinergic actions, according to a 2004 article in "Primary Care Companion to the Journal of Clinical Psychiatry."
Anticholinergics impair the ability of the eyes to adjust for distant vision and to constrict the pupils. Sensitivity to light can develop. Driving and other potentially dangerous activities that rely on clear eyesight should be avoided.