Atropine is an antimuscarinic receptor blocker that is commonly used to treat bradycardia and ophthalmic conditions. It is also used as an antidote to treat the toxicity of Acetylcholine esterase inhibitors organophosphate and beta blockers.
Atropine can decrease urgency of urine in a person causing urinary retention. It can also help increase the activity of the heart; it causes mydriasis as well constipation in persons taking atropine.
Side effects are undesirable effects of drugs. Any of these options can become a side effect to a person based on the reason he or she is using this medication.
For example, a person using atropine for an ophthalmic condition will find constipation, urinary retention and increased pulse to be a side effect of this medication as these effects are not required.