Atropine is a medication used to treat certain types of nerve agent and pesticide poisonings, some types of slow heart rate, and to decrease saliva production during surgery. It is typically given intravenously or by injection into a muscle. Eye drops are also available which are used to treat uveitis and early amblyopia. The intravenous solution usually begins working within a minute and lasts half an hour to an hour. Large doses may be required to treat poisonings. Common side effects include a dry mouth, large pupils, urinary retention, constipation, and a fast heart rate. It should generally not be used in people with angle closure glaucoma. While there is no evidence that its use during pregnancy causes birth defects, it has not been well studied. It is likely safe during breastfeeding. It is an antimuscarinic (also known as an anticholinergic) that works by inhibiting the parasympathetic nervous system. Atropine occurs naturally in a number of plants of the nightshade family including deadly nightshade, Jimson weed, and mandrake. It was first isolated in 1833. Atropine is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system. It is available as a generic medication and not very expensive. A one-milligram vial costs wholesale in the developing world between 0.06 and 0.44 USD.