NFL players have been told that they can keep using smelling salts for a mid-game jolt — but they’ll have to ‘bring their own’.

Earlier this week, the league told clubs that they were henceforth prohibited from providing smelling salts, ammonia inhalers or any similar products during pregame warm-ups, at half-time or at any point on the sideline during a game. The memo, obtained by NPR, cited a 2024 U.S. Food and Drug Administration (FDA) warning that there was no evidence that the products are safe or effective for boosting alertness — and, notably, that they could actually mask symptoms of concussion.

The sudden rule shift sparked confusion after players, most vocally San Francisco 49ers tight end George Kittle, began claiming that the NFL had ‘made [smelling salts] illegal’. Kittle, in his inimitable style, proclaimed himself ‘distraught’ as he admittedly uses the salts multiple times each game.

“I considered retirement,” he joked after crashing an NFL Network set at 49ers practice to break the news of the ‘ban’. “We have to figure out a middle ground.”

By Wednesday night that middle ground appeared to have been reached, albeit mostly by clearing up the terms of the ruling. The NFL Players Association (NFLPA) stepped in to set the record straight and, in a memo to players obtained by the Associated Press, clarified that the league ‘does not prohibit player use of these substances, but rather it restricts clubs from providing or supplying them in any form’.

Smelling salts — known, chemically, as ammonium carbonate — have been a sideline staple for decades. When mixed with water in single-use capsules, they release ammonia gas, which triggers a reflexive inhalation, raising respiratory rate, cerebral blood flow and heart rate. Athletes say that, along with a jolt of energy, the salts can also aid mental sharpness.

“It’s really gross… like you’re really close up to cat urine,” said Laura Boxley, a neuropsychologist at Ohio State University’s Wexner Medical Center, told an NPR interview. “However, some athletes are using them with much higher frequency than intended.”

Originally known as ‘salt of hartshorn’ in the 17th century, when they were derived from deer antlers, smelling salts were historically used to revive the fainted, and are still stocked in many airline first aid kits, per Federal Aviation Administration rules.

Despite their reputation in sports culture, however, research shows no measurable performance benefit ‘despite elevated arousal and an associated perception of performance enhancement’. Health experts also warn that the perceived boost comes with risks, with inappropriate or frequent use causing shortness of breath, seizures, migraines and, in the case of athletes with concussions, more serious dangers. Because smelling salts artificially elevate arousal levels, Boxley says they can mask symptoms like confusion or dizziness, delaying diagnosis and treatment. The ammonia vapour can also trigger a sharp, involuntary head movement, potentially exacerbating head or neck injuries.

The NFL’s renewed caution follows growing concern over brain injuries in football, with estimates suggesting one concussion occurs every two NFL games.

“Whenever you’re using a tool outside of its recommended use, you’re in kind of uncharted territory,” Boxley stressed. “In the absence of evidence that it actually improves anything, I think it’s reasonable to prioritise somebody’s health over an unproven substance.”

Under the new rule, however, players like Kittle can continue using smelling salts and other similar products, but teams can no longer provide them, effectively absolving the league of responsibility should there be any adverse effects.