A foreign body (FB) is any object originating outside the body of an organism. In machinery, it can mean any unwanted intruding object. Most references to foreign bodies involve propulsion through natural orifices into hollow organs. Foreign bodies can be inert or irritating. If they irritate they will cause inflammation and scarring. They can bring infection into the body or acquire infectious agents and protect them from the bodys immune defenses. They can obstruct passageways either by their size or by the scarring they cause. Some can be toxic or generate toxic chemicals from reactions with chemicals produced by the body, as is the case with many examples of ingested metal objects. With sufficient force (as in firing of bullets), a foreign body can become lodged into nearly any tissue. Gastrointestinal tract
One of the most common locations for a foreign body is the alimentary tract. It is possible for foreign bodies to enter the tract from the mouth or rectum. Both children and adults experience problems caused by foreign objects becoming lodged within their bodies. Young children, in particular, are naturally curious and may intentionally put shiny objects, such as coins or button batteries, into their mouths. They also like to insert objects into their ear canals and nostrils. The severity of a foreign body can range from unconcerning to a life-threatening emergency. For example, a coin causes local pressure on the tissue but generally is not a medical emergency to remove.
It is used to prevent or treat dry mouth, particularly in Sjögren syndrome, but also as a side effect of radiation therapy for head and neck cancer.It may be used to help differentiate Adie syndrome from other causes of unequal pupil size.It may be used to treat a form of dry eye called aqueous deficient dry eye (ADDE)

Surgery
Pilocarpine is sometimes used immediately before certain types of corneal grafts and cataract surgery. It is also used prior to YAG laser iridotomy. In ophthalmology, pilocarpine is also used to reduce symptomatic glare at night from lights when the patient has undergone implantation of phakic intraocular lenses; the use of pilocarpine would reduce the size of the pupils, partially relieving these symptoms. The most common concentration for this use is pilocarpine 1%. Pilocarpine is shown to be just as effective as apraclonidine in preventing intraocular pressure spikes after laser trabeculoplasty. Presbyopia
In 2021, the US Food and Drug Administration approved pilocarpine hydrochloride as an eyedrop treatment for presbyopia, age-related difficulty with near-in vision. It works by causing the pupils to constrict, increasing depth of field, similar to the effect of pinhole glasses. Marketed as Vuity, the effect lasts for more than 6 hours. Other
Pilocarpine is used to stimulate sweat glands in a sweat test to measure the concentration of chloride and sodium that is excreted in sweat. It is used to diagnose cystic fibrosis. Adverse effects
Use of pilocarpine may result in a range of adverse effects, most of them related to its non-selective action as a muscarinic receptor agonist.