Smelling salts

Smelling salts, also known as spirit of hartshorn or sal volatile, are chemical compounds used for arousing consciousness.^[1] The usual active compound is ammonium carbonate, a colorless-to-white, crystalline solid ((NH₄)₂CO₃).^[1] Because most modern solutions are mixed with water, they should more properly be called "aromatic spirits of ammonia."^[1] Modern solutions may also contain other products to perfume or act in conjunction with the ammonia, such as lavender oil or eucalyptus oil.^[2]

History

Smelling salts have been used since Roman times and are mentioned in the writings of Pliny as Hammoniacus sal.^[1] Evidence exists of use in the 13th century by alchemists as sal ammoniac.^[1]

In the 17th century, the distillation of an ammonia solution from shavings of harts' (deer) horns and hooves led to the alternative name for smelling salts as spirit or salt of hartshorn.^[1]

Smelling salts have also been known as 'sal volatile', for their ability to produce a reaction.^[3]

They were widely used in Victorian Britain to revive fainting women, and in some areas constables would carry a container of them for the purpose.^[4]

The use of smelling salts was widely recommended during the Second World War, with all workplaces advised by the British Red Cross and St. John Ambulance to keep 'sal volatile' in their first aid boxes.^[5] Nowadays, their use and prevalence has dramatically decreased.

Usage

Smelling salts are often used on athletes (such as boxers) when they are knocked unconscious or semi-conscious to arouse consciousness and restore mental alertness.^[1]

They are also used in competitions (such as powerlifting, strong man and ice hockey) to "wake up" competitors to perform better.^[1][6] Famous athletes such as Brett Favre, Peyton Manning, Carlos Boozer, and Tom Brady have been seen using smelling salts on the sidelines.^{[7][8][9][10]}

They are also still used for people feeling faint,^[11][12][13] or who have fainted, either administered by others, or self administered, with some at-risk groups, such as pregnant women, sometimes advised to keep them close to hand.^[14]

Physiological action

Smelling salts release ammonia (NH₃) gas, which triggers an inhalation reflex (that is, cause the muscles that control breathing to work faster^[6]) by irritating the mucous membranes of the nose and lungs.^[6] Additionally, the irritant elevates the heart rate, blood pressure, and brain activity by activating the sympathetic nervous system. Many benign fainting events are caused by excessive parasympathetic and vagal activity that dilates blood vessels, slows the heart, and decreases perfusion of the brain.^[15] The sympathetic irritant effect is exploited to counteract these vagal parasympathetic effects and thereby reverse the faint.^{[citation needed]}

Risks

Ammonia gas is toxic in large concentrations for prolonged periods^[1] and can be fatal.^[13] Since smelling salts produce only a small amount of ammonia gas, no adverse health problems from their use have been reported.^[1] However, a high concentration of inhaled ammonia might burn the nasal or oral mucosa.^[1]

The use of ammonia smelling salts to revive people injured during sport is not recommended because it may inhibit or delay a proper and thorough neurological assessment by a healthcare professional,^[1] and some governing bodies recommend specifically against it.^[16] The irritant nature of smelling salts means that they can exacerbate any pre-existing cervical spine injury by causing reflex withdrawal from them.^[1]

References