Ammonia inhalants, historically known as “smelling salts,” are chemical preparations designed to produce a rapid, temporary stimulant effect. The active ingredient is typically ammonium carbonate, often mixed with a diluted solution of ammonia and sometimes aromatic substances like perfume or lavender oil. When the sealed capsule or vial is broken, the resulting chemical reaction releases ammonia gas, which possesses a sharp, pungent, and acrid odor. This substance has been used as a restorative agent since at least the 13th century, with its use becoming widespread in Victorian times to quickly revive individuals who had fainted.
Primary Use in Syncope and Athletics
The original medical application of ammonia inhalants is the treatment of syncope, which is a temporary loss of consciousness, or fainting. The strong irritant vapor is intended to provoke an immediate reaction that restores consciousness when blood flow to the brain suddenly drops. This use has largely faded in modern medical practice, though it remains the only use for which the inhalants are approved by the Food and Drug Administration.
A more common use today occurs outside of clinical settings, particularly in high-intensity sports like powerlifting, hockey, and American football. Athletes use the inhalants to achieve a temporary boost in arousal or alertness before a competition or a heavy lift. The intent is to overcome perceived sluggishness or to psych themselves up for a short burst of maximal effort.
While athletes often report a feeling of enhanced focus and energy, scientific evidence supporting a true performance-enhancing effect remains limited. The effect is largely considered one of heightened psychological arousal, which helps some athletes feel more prepared for the task ahead. This non-medical application has drawn scrutiny due to the lack of regulation and potential for misuse in competitive environments.
Physiological Mechanism of Action
The physiological effect of ammonia inhalants is not due to direct chemical stimulation of the brain, but rather an intense irritant reflex originating in the nasal cavity. When the ammonia gas is inhaled, it aggressively irritates the delicate mucous membranes lining the nose and upper respiratory tract. This chemical irritation activates the trigeminal nerve, the fifth cranial nerve responsible for transmitting sensory information from the face and head.
The trigeminal nerve stimulation acts as a sudden, intense noxious stimulus that triggers an immediate protective reflex. This reflex forces an involuntary gasp and a rapid change in breathing patterns known as hyperventilation. The involuntary deep inhalation sends a rush of oxygenated air into the lungs, which increases the oxygen saturation in the blood sent to the brain.
This reflex-driven increase in respiratory rate and the perception of pain also activate the body’s sympathetic nervous system, initiating a “fight or flight” response. Sympathetic activation results in a cascade of physiological changes, including an elevation in heart rate and cerebral vasodilation, which increases blood flow to the brain. This sequence of events forcibly restores alertness or consciousness.
Safety Concerns and Administration Risks
The use of ammonia inhalants carries several significant risks, primarily stemming from the corrosive nature of ammonia and the forceful reflex it induces. Holding the inhalant too close to the nostrils can lead to chemical burns or damage to the sensitive nasal passages and the lining of the respiratory tract. Excessive or chronic use of the irritant vapor may also lead to long-term respiratory issues.
A more serious concern arises in athletic settings where the inhalant is used on a player who may have sustained a head or neck injury, such as a concussion. The involuntary, sudden head movement that occurs when a person reacts to the pungent odor can potentially exacerbate an undiagnosed spinal or cervical trauma. This risk is so pronounced that many sports medicine professionals strongly advise against their use when managing any suspected neurological injury.
Furthermore, the temporary, forced increase in alertness produced by the inhalant can dangerously mask the signs and symptoms of a more serious underlying medical condition. By artificially elevating the user’s level of arousal, the inhalants may delay the accurate diagnosis and treatment of conditions like a concussion. This masking of symptoms poses a risk of further injury and complicates the neurological assessment process, potentially leading to an unsafe return to activity.