What do they put under your nose when you pass out?

September 21, 2025 •

4 min read

Historically, smelling salts, or ammonia inhalants, have been used since the 13th century to revive people who have fainted.

So, what do they put under your nose when you pass out? The traditional answer is a solution of ammonia, which provides a strong, acrid odor designed to startle a person back to consciousness.

Quick Summary

The substance commonly held under the nose of someone who has passed out is a chemical irritant, typically ammonia-based smelling salts.

These irritant fumes cause a sharp inhalation reflex, which increases a person's breathing rate, blood pressure, and heart rate to help restore consciousness.

Key Points

Smelling Salts: The substance put under a person's nose when they pass out is a smelling salt, also known as an ammonia inhalant.
Mechanism of Action: The ammonia fumes irritate the nasal and lung membranes, triggering a sharp inhalation reflex that increases breathing and heart rate.
Modern Medical Caution: Today, medical professionals advise against the use of smelling salts, preferring safer methods like elevating the legs to treat fainting.
Key Risks: Misuse can lead to respiratory damage, mask serious head injuries, and cause dangerous neck jerks if a spinal injury is present.
First Aid Alternatives: The safest procedure for fainting is to lay the person down with their legs elevated and to seek emergency help if consciousness is not quickly regained.
Performance vs. Medical Use: While popular in some sports for an alertness boost, there is little evidence of genuine performance enhancement, and the practice is medically unadvised, especially after head trauma.

Understanding Smelling Salts and Ammonia Inhalants

Smelling salts, also known as ammonia inhalants, are a mixture of ammonium carbonate and perfume, or simply diluted ammonia in water and alcohol.

When a person inhales the vapors, the ammonia irritates the membranes inside the nose and lungs. This irritation triggers an inhalation reflex, causing an involuntary and sharp intake of breath. This rapid breathing increases oxygen flow to the brain, which, in turn, stimulates the sympathetic nervous system and triggers a "fight-or-flight" response. This process can cause someone who is feeling faint or has briefly lost consciousness to wake up and feel more alert.

The Physiological Mechanism: How It Works

When ammonia gas enters the nasal passages, it directly stimulates the trigeminal nerve. This is the largest cranial nerve and is responsible for sensations in the face. The irritation of this nerve sends a signal to the brainstem, which controls basic life functions like breathing. The brainstem then triggers the inhalation reflex, forcing a deep and rapid breath.

This is why smelling salts are often associated with a strong, immediate, and jarring reaction. The physiological response includes:

Increased Respiratory Rate: The primary effect is a change in breathing pattern, forcing deeper, faster breaths.
Elevated Heart Rate and Blood Pressure: The sympathetic nervous system activation results in a temporary increase in heart rate and blood pressure.
Adrenaline Release: This stimulation causes a temporary surge of adrenaline, contributing to a heightened state of alertness.

Modern Medical Perspective: Efficacy and Alternatives

While smelling salts have a long history, their use in modern medicine has declined significantly. The traditional advice for someone feeling faint is to lie down and elevate the legs, which naturally helps blood flow back to the brain. This method is considered safer and avoids the risks associated with chemical irritants.

Most medical professionals today advise against using smelling salts due to potential health risks, especially if the underlying cause of unconsciousness is unknown. The practice has shifted more toward simple, non-invasive first aid techniques.

For current and safe first aid guidance for fainting, refer to the Red Cross Guidelines for Fainting.

Risks and Safety Concerns Associated with Smelling Salts

Although generally safe for occasional, directed use, smelling salts carry several risks, particularly when misused or overused. It's crucial to understand these dangers before ever considering their application:

Respiratory Irritation: The highly corrosive nature of ammonia can cause chemical burns to the nasal passages, throat, and lungs, especially with repeated use or if held too close to the nose.
Masking Serious Conditions: In athletic contexts, using smelling salts after a head injury could mask symptoms of a more serious issue, such as a concussion. This can lead to an athlete returning to play too early and risking further injury.
Spinal Injury Risk: The involuntary head and neck jerk that can occur when inhaling smelling salts can be dangerous if a spinal injury is present, potentially exacerbating the trauma.
Risk of Overdose: Inhalation of high concentrations of ammonia can be extremely toxic and potentially fatal. While accidental fatality from proper use is rare, holding the salts too close or using concentrated forms increases this risk.
Lack of Evidence for Performance Enhancement: Despite popular use among some athletes, there is little scientific evidence to support the claim that smelling salts improve athletic performance, suggesting the effect is often psychological or a placebo effect.

Smelling Salts in Athletics vs. Medical Practice


Feature	Medical Use (Fainting)	Athletic Use (Performance)
Primary Goal	To quickly restore consciousness from a simple faint.	To boost alertness, focus, and adrenaline for a short period.
Medical Stance	Largely discouraged in favor of safer methods like lying down and elevating legs.	Not recommended, especially after a head injury, due to risk of masking symptoms.
Physiological Effect	Triggers an involuntary inhalation reflex to increase oxygen to the brain.	Causes a temporary increase in heart rate, blood pressure, and alertness.
Key Risk	Inappropriate use on a person with a different underlying condition or injury.	Masking serious injury symptoms (e.g., concussion) and potential for respiratory damage.
Common Scenario	Historically used for fainting or "swooning" spells in non-trauma cases.	Common in sports like powerlifting and football, but often based on folklore rather than science.

Proper First Aid Protocol for Fainting

Given the risks, it's essential to know the correct first aid procedure for a person who has passed out, which does not involve smelling salts:

Lay the person down: Position them on their back to improve blood flow to the brain.
Elevate their legs: If possible, raise their legs about 12 inches above heart level. This is the most effective and safest method to treat simple fainting.
Loosen tight clothing: Undo any tight belts or collars to ensure proper circulation and breathing.
Check for breathing: Monitor their breathing and responsiveness. If they do not regain consciousness within a minute, or if breathing stops, call for emergency medical help immediately.
Position them for recovery: If they regain consciousness but seem unwell, turn them onto their side in the recovery position to prevent choking if they vomit.

Conclusion

In conclusion, the substance most people associate with being put under the nose of someone who has passed out is a smelling salt or ammonia inhalant. While effective at providing a strong, irritating stimulus that triggers a person to wake up, modern medical advice emphasizes caution. Safer and more effective first aid methods are widely recommended, and the risks of respiratory damage and masking serious underlying conditions are significant, particularly in cases of head trauma. For a simple faint, elevating the legs is the preferred approach, and for any extended period of unconsciousness, immediate professional medical evaluation is necessary.

Frequently Asked Questions

No, smelling salts are not the only, or even the recommended, option. The safest and most common first aid method for a simple faint is to lay the person down and elevate their legs to improve blood flow to the brain.

Yes, it can be dangerous. The ammonia can irritate or burn the nasal passages and lungs. More seriously, the jerk reaction can worsen a potential spinal injury, and the salts can mask symptoms of a concussion, delaying proper medical assessment.

Instead of using smelling salts, lay the person on their back, elevate their legs about 12 inches, and loosen any tight clothing. This helps restore blood flow to the brain naturally and safely. If they don't regain consciousness quickly, call for emergency medical help.

Some athletes, particularly in sports like powerlifting and football, use smelling salts to get a temporary burst of alertness and adrenaline. They believe it boosts focus and performance, but the scientific evidence for this is limited, and the effect is often considered psychological or a placebo.

Smelling salts typically consist of ammonium carbonate, which releases ammonia gas when mixed with water. Modern versions may also include perfume or other aromatic spirits like eucalyptus oil to mask the pungent odor.

A simple faint (syncope) usually lasts only a few moments. If a person does not regain consciousness within about a minute, or if they have other concerning symptoms like a head injury, blurred vision, slurred speech, or breathing problems, it may be a more serious condition. Always call for emergency medical help in such cases.

There is no definitive evidence to suggest that proper, directed use of smelling salts kills brain cells. However, improper use or excessive exposure to high concentrations of ammonia could potentially cause harm to the respiratory system.