Smelling salts contain one key active ingredient: ammonia. The traditional form is ammonium carbonate, a crystalline salt mixed with perfume. Most modern versions sold online are simply dilute ammonia dissolved in a mixture of water and ethanol. Either way, it’s the sharp burst of ammonia gas that does the work.
The Active Ingredient
Ammonium carbonate is the classic compound at the heart of smelling salts. When exposed to air, it breaks down and releases ammonia gas, which produces that unmistakable, eye-watering smell. The chemical formula is (NH4)2CO3·H2O, but thinking of it as a solid that slowly releases ammonia fumes is the practical way to understand it.
The other common formulation skips the crystal entirely. These products use ammonia already dissolved in water and ethanol, sometimes called aromatic ammonia spirit. This liquid version is what you’ll find in most single-use capsules and bottled inhalants. Commercially available products typically release between 50 and 100 parts per million of ammonia vapor, a concentration designed to be potent enough to trigger a reaction without causing tissue damage.
Secondary Ingredients
Beyond ammonia, smelling salts contain a few supporting ingredients. Ethanol (alcohol) serves as a solvent, helping to stabilize the ammonia in liquid form and control how quickly it evaporates. Perfumes or essential oils have been part of the recipe since at least the 17th century, originally added to make the experience slightly less harsh. The term “smelling salts” actually came about when ammonium carbonate crystals were first blended with fragrances for use as a restorative. Some modern athletic-grade products skip the perfume entirely, prioritizing a stronger ammonia hit.
How They Work in Your Body
When you inhale ammonia vapor, it doesn’t just smell bad. The gas irritates the nerve endings inside your nose and eyes, specifically the free endings of sensory nerves connected to the trigeminal nerve. This is the same nerve responsible for the burning sensation you feel from wasabi or raw onion. The irritation triggers a rapid, involuntary inhalation reflex, which increases your breathing rate, raises your heart rate, and briefly elevates blood pressure. The result is a jolt of alertness.
This reflex can also cause your eyes to water, even if the ammonia never directly contacts them. At higher concentrations, it can provoke coughing as the irritation reaches deeper into the airway. The entire response is essentially your body’s alarm system reacting to a chemical irritant, not a stimulant in the way caffeine works on your brain.
Why Athletes Use Them
If you’ve seen powerlifters or football players sniffing something from a small capsule before a lift or a play, that’s almost certainly an ammonia inhalant. The appeal is straightforward: the sharp burst of alertness and the spike in breathing and heart rate can help an athlete feel more “switched on” before a maximal effort. Smelling salts are not banned in most sports, including the NFL and competitive powerlifting.
Whether they actually improve physical performance is a separate question from whether they make you feel more alert. The physiological response is real, but it’s brief. Most athletes describe the effect as psychological preparation, a way to override nervousness or fatigue in the seconds before a big moment.
Risks of Frequent or Heavy Use
At the concentrations found in commercial products (50 to 100 ppm), a single use is unlikely to cause lasting harm. But ammonia is genuinely toxic at higher doses. Exposure to large amounts can damage the lining of the airways, potentially causing bronchitis, fluid buildup in the lungs, or permanent respiratory injury. The gap between a commercial smelling salt and a dangerous exposure is wide, but using concentrated or homemade ammonia products narrows that gap considerably.
Repeated use also carries risk. The mucous membranes inside your nose are sensitive tissue, and frequent ammonia exposure can irritate or inflame them over time. People with asthma, bronchitis, emphysema, or other chronic lung conditions face a higher risk, as ammonia can worsen airway constriction. Those with eye conditions should also be cautious, since the trigeminal nerve response can affect the eyes even at low concentrations.
The FDA has issued warnings about unapproved inhalant products marketed for “alertness” and “energy boosting,” noting reports of adverse events including shortness of breath, seizures, migraines, vomiting, and fainting. These products had not been demonstrated to be safe or effective for their marketed uses, and warning letters were sent to the companies selling them.
Traditional vs. Modern Products
The original smelling salts date back to at least the 1600s, when ammonia was distilled from animal horns and hooves, earning the nickname “spirit of hartshorn.” Once chemists identified the resulting compound as ammonium carbonate, it was refined into the small, perfumed preparations that Victorian-era physicians waved under the noses of fainting patients.
Today’s products come in two main forms. Single-use capsules contain a small amount of ammonia solution sealed inside a crushable wrapper. You snap it, and the vapor escapes. Bottled aromatic ammonia spirit is the liquid version, typically kept in a small container and held briefly under the nose. Both deliver the same active compound. The difference is convenience and concentration, with capsules offering a more controlled, single dose and bottles allowing repeated use but with less predictable strength over time as the ammonia slowly escapes.