The active agents in belladonna, atropine, hyoscine (scopolamine), and hyoscyamine, have anticholinergic properties. The symptoms of belladonna poisoning include dilated pupils, sensitivity to light, blurred vision, tachycardia, loss of balance, staggering, headache, rash, flushing, severely dry mouth and throat, slurred speech, urinary retention, constipation, confusion, hallucinations, delirium, and convulsions. In 2009, "A. belladonna" berries were mistaken for blueberries by an adult woman; the six berries she ate were documented to result in severe anticholinergic syndrome. The plant's deadly symptoms are caused by atropine's disruption of the parasympathetic nervous system's ability to regulate involuntary activities, such as sweating, breathing, and heart rate. The antidote for belladonna poisoning is an anticholinesterase (such as physostigmine or pilocarpine), the same as for atropine.