smelling salts

smelling salts, any of several different preparations of ammonia-based product and other ingredients used to revive a person affected by syncope (fainting). Historically, smelling salts contained ammonium carbonate and perfume; modern preparations typically consist of ammonia dissolved in water and ethanol, sometimes infused with a scented oil, such as eucalyptus. The salts release ammonia gas that irritates the nose and lung membranes, triggering an inhalation reflex, which prompts the muscles that control breathing to work faster and helps restore oxygen flow to the brain and body.

History

Ammonium chloride, the salt of ammonia and hydrogen chloride, has been known since at least the time of Roman scholar Pliny the Elder, who wrote about “sal ammoniac” (also called sal hammoniacus, or hammoniacus sal) in his encyclopedic work Natural History (completed in 77 ce). The ancient Romans presumably used the substance as a restorative. About the 9th century, Arab scholars further reported on ammonium chloride, referring to the compound as nushadhir, and in the Middle Ages in Europe, ammonia derived from fermented urine was used to modify the color of vegetable dyes used in textiles. In the 17th century chemists obtained ammonium carbonate by crystallizing an aqueous solution of ammonia that was obtained through the distillation of horn and hoof shavings from harts (male red deer). The carbonate was initially called “spirits of hartshorn.” The addition of perfume to the ammonium carbonate resulted in a preparation that became known as smelling salts.

By the 18th century several medical journals included mention of the restorative properties of smelling salts. During this time, vinaigrettes, which were specially designed decorative containers, became a fashionable accessory among women. The containers housed a sponge infused with smelling salts; when opened, the bottle could simply be waved under the nose when the individual was feeling faint.

During World War II, the British Red Cross and St. John Ambulance produced first aid kits that included smelling salts. The kits were used by medics in the field. By the mid-20th century, advancements in modern medicine led to the introduction and use of other treatments for syncope, among them oxygen therapy and intravenous medications. It was also recognized that persons who are feeling faint often benefit from simply lying down and breathing deeply, which can help prevent passing out.

In the late 1960s smelling salts became widely used in sports, particularly boxing, football, and hockey, owing to the idea that stimulation of the inhalation reflex could counteract the effects of head trauma. Athletes later began using smelling salts to boost their performance, under the misguided idea that the inhalation reflex provides a burst of energy and increases alertness. Research has shown, however, that although ammonia inhalation may have some effect on repetitive high-intensity exercise, it does not improve performance involving short bursts of high-intensity physical effort, nor does it benefit head trauma. In fact, inhalation of ammonia can potentially worsen underlying brain injury.

Side effects

The use of smelling salts causes a temporary increase in heart rate and oxygen intake, reinvigorating individuals and potentially producing a sensation akin to the fight-or-flight response. Side effects can occur, however, including chemical burns to the eyes or skin and burns to the nasal passages from repeated use. Some persons may experience a whiplash effect from the inhalation reflex, causing neck injury or exacerbating an underlying neck, back, or spine injury. Smelling salts may also worsen symptoms of existing respiratory conditions, such as asthma or bronchitis.