Smelling salts are not dangerous for most healthy people when used occasionally and at the proper distance, but they do carry real risks with frequent use, improper technique, or underlying health conditions. The active ingredient is ammonia gas, a caustic irritant that can burn your nasal passages, trigger asthma attacks, and cause eye damage if you’re not careful.
What Smelling Salts Actually Do
A typical smelling salt capsule contains about 15% ammonium carbonate and 10% sodium carbonate mixed with alcohol. When crushed or opened, these chemicals react with moisture in the air to release ammonia gas. That sharp, eye-watering smell isn’t just unpleasant. It’s a chemical irritant triggering a reflex in your body.
When ammonia hits the moist lining of your nose, it activates pain and irritation receptors connected to the trigeminal nerve, the largest nerve in your skull. This nerve runs through your nasal passages, eyes, and face, and when it fires, your body responds with a jolt: your heart rate spikes, your breathing quickens, and your blood pressure rises. That’s why smelling salts can snap someone out of a faint or give a powerlifter a burst of alertness before a heavy lift. The effect isn’t a stimulant in the traditional sense. It’s a pain response your body interprets as an emergency.
Short-Term Side Effects
Even a single use can cause noticeable irritation. When ammonia contacts the wet tissue in your eyes, nose, and throat, it forms ammonium hydroxide, a caustic chemical that burns on contact. Common reactions include stinging or watering eyes, coughing, sneezing, and a burning sensation in your nose and throat. Your heart rate temporarily increases. These effects are short-lived in most people and resolve within minutes.
The bigger immediate risk is chemical burns. If you hold a capsule or bottle too close to your face, concentrated ammonia can burn the inside of your nostrils, your eyes, or your skin. The recommended safe distance is 4 to 6 inches (10 to 15 cm) from your nostrils. Many people, especially in gym settings, crack a capsule and shove it directly under their nose, which dramatically increases the concentration of ammonia hitting their tissue.
Risks of Repeated Use
Occasional use is unlikely to cause lasting harm for a healthy person. Frequent, repeated use is a different story. According to the Agency for Toxic Substances and Disease Registry, repeated ammonia exposure can cause chronic irritation of the respiratory tract, leading to persistent cough, asthma, and lung scarring (fibrosis). Chronic irritation of the eye membranes and skin inflammation have also been documented in people with ongoing ammonia exposure.
The Cleveland Clinic specifically notes that repeated use of smelling salts can cause burns inside your nasal passages. These aren’t theoretical risks pulled from industrial exposure data alone. They’re relevant to anyone snapping a capsule before every set at the gym, multiple times per week.
OSHA limits workplace ammonia exposure to 25 ppm over an eight-hour shift and 35 ppm for any 15-minute window. While exact ppm data for a single smelling salt capsule at close range isn’t well documented, the concentration is high enough to produce an immediate pain response, which tells you it’s well above comfortable exposure levels.
Who Should Avoid Them Entirely
Smelling salts are explicitly not recommended for people with:
- Asthma, emphysema, or chronic lung disease. Ammonia can trigger bronchospasm and worsen existing airway inflammation. What feels like a harmless jolt to a healthy person could send someone with asthma into a serious attack.
- Heart disease or high blood pressure. The sudden spike in heart rate and blood pressure is the entire mechanism of action. For someone with cardiovascular problems, that spike carries genuine risk.
- Eye conditions. Ammonia vapor irritates eye tissue and, in concentrated exposure, can cause corneal damage.
- Ammonia allergy or sensitivity to strong odors. Some people experience allergic reactions to inhaled ammonia beyond the normal irritation response.
Older adults who faint should also be cautious. Fainting in older people often signals a more serious underlying condition, and using smelling salts to “fix” the problem can mask something that needs medical evaluation.
Smelling Salts in Sports
Smelling salts are popular in powerlifting, strongman, football, and hockey. Athletes use them to feel more alert and aggressive before a big effort. The effect is real: the ammonia triggers a genuine physiological arousal response. But there’s no evidence that this translates into stronger muscles or better performance. What you’re getting is a shot of adrenaline from a pain stimulus.
One concern specific to contact sports is using smelling salts after a head injury. The alertness boost can mask concussion symptoms, making an athlete feel ready to return to play when their brain is still vulnerable. This is dangerous, and most sports medicine professionals advise against using smelling salts to assess or manage a head injury.
How to Reduce Risk if You Use Them
If you choose to use smelling salts, the single most important thing is distance. Hold the capsule or bottle 4 to 6 inches from your nostrils, not directly under your nose. Inhale slowly rather than taking a deep, aggressive sniff. Keep it away from your eyes and skin entirely, as direct contact can cause burns.
Limit how often you use them. Reserving smelling salts for competition or occasional max-effort attempts is meaningfully different from cracking a capsule before every working set, five days a week. Low concentrations of ammonia cause irritating but self-limiting symptoms like coughing and eye burning. Concentrated or frequent exposure is where permanent damage to your lungs and nasal tissue becomes possible.