It didn’t take long for Knicks fans to get an early surprise in Game 3 of the NBA Finals against the Spurs.

As guard Josh Hart’s name was announced, cameras caught the 31-year-old taking a quick sniff from a small black tube before jogging onto the court.

The moment immediately set social media buzzing, with viewers speculating Hart had just taken a hit of smelling salts — and he wouldn’t be the only one.

The pungent inhalants have become a familiar pregame ritual across American sports and around the world, with athletes swearing by them as a quick way to achieve a mental edge.

San Francisco 49ers running back Christian McCaffrey, San Jose Sharks center Macklin Celebrini and Knicks forward Karl-Anthony Towns have all been caught on camera taking a whiff of what appears to be smelling salts during games (though they haven’t confirmed that’s what they’re using).

The habit has deep roots in football, powerlifting and hockey, but experts say that they are increasingly being spotted in the hands of soccer players.

Premier League stars like Everton’s Richarlison and Mason Holgate have been spotted inhaling the powder in the tunnel before kickoff, while rumors swirled that US national team defender Walker Zimmerman did the same during a 2022 showdown with Mexico.

The trend has even reached soccer’s biggest stage. After Russia’s surprise run to the 2018 World Cup quarterfinals, the team’s doctor was left answering questions about his players’ use of the substances.

With the next World Cup underway, a number of players set to take the field — including England goalkeeper Jordan Pickford — have been seen using smelling salts in the past.

So what exactly are these inhalants, and why do they stir debate? The Post spoke with three experts to find out.

What are smelling salts?

They’re over-the-counter inhalants made from a mixture of ammonia and other chemicals that deliver a powerful, nose-burning jolt.

The most common version comes in a small dark plastic bottle filled with a white powder that’s opened and sniffed. They also come in crushable capsules or pre-moistened towelettes that can be snapped and waved under the nose.

“When inhaled, the ammonia gas irritates the nasal passages and respiratory system, triggering an involuntary inhalation reflex,” Dr. Mark Kovacs, a performance physiologist and former senior director of sport science and health for the Cleveland Cavaliers, told The Post.

“This creates a very short-term increase in breathing rate, alertness and sympathetic nervous system activation.”

That sudden rush of alertness is what makes smelling salts popular among athletes today. But long before becoming a fixture in locker rooms, smelling salts were used as a medical tool.

“They were initially developed for patients who had fainted, to wake them up,” said Dr. Spencer Stein, orthopedic surgeon and sports medicine specialist at NYU Langone.

“But they’re falling out of favor. We’re not really using them in medicine anymore, there are other ways to do that.”

Why do athletes use smelling salts?

“When athletes use smelling salts before competition, they are usually looking for a rapid increase in alertness, arousal, aggression or perceived readiness,” Kovacs said.

“The appeal is that the effect feels immediate,” he explained. “In sports such as football or powerlifting, where a single explosive effort may matter, athletes may believe it helps them feel more locked in.”

What does the science say about them?

“There is little to no evidence that smelling salts offer any performance advantage,” said Dr. Tony Wanich, a sports medicine surgeon at Hospital for Special Surgery.

The only proven benefit, he noted, is psychological. 

“The momentary increase in alertness and focus is short lived, but does often provide athletes with the sense of being better prepared mentally for competition,” Wanich said. 

“Athletes have this perception of increased performance after the use of the smelling salts without any objective data of actual improved performance.”

Are smelling salts dangerous?

While smelling salts may seem harmless, experts say there are legitimate risks.

“Oftentimes, when a player has sustained a concussion and feels dazed, the use of smelling salts can mask these symptoms and make them appear more alert than they really are,” Wanich said. “The risk of a secondary head injury in this situation can be catastrophic.”

There’s also the body’s immediate physical reaction to consider. When inhaled, smelling salts trigger an involuntary reflex that can cause the head and neck to jerk backward suddenly.

“If somebody has a spinal injury and it’s given to them, I can see that being an issue,” Stein said.

Repeated use may pose additional problems. “There seems to be tolerance component to it, so people that use it need a lot more over time,” Stein said. “If you use it too much, you can get burns of the nasal passage and the airway and even the lungs.”

For athletes with asthma, that irritation can be especially problematic. There have also been reports of allergic reactions linked to smelling salts.

In 2024, the FDA warned consumers against using inhalants marketed to boost alertness or energy, citing reports of shortness of breath, seizures, migraines, vomiting, diarrhea and fainting.

Last year, the NFL banned teams from providing smelling salts to players, citing both the FDA warning and concussion concerns.

Will we see smelling salts at the 2026 FIFA World Cup?

“Smelling salts are much more embedded in American football, hockey and powerlifting than in soccer,” Kovacs said.

That’s largely because the demands of the sport are different.

“A match requires repeated sprinting, decision-making, technical skill, aerobic fitness, tactical awareness, and emotional control over 90-plus minutes,” Kovacs said. “A brief jolt of arousal is not the same as improved performance.”

Still, smelling salts appear to be gaining traction in the world’s most popular sport.

“We are seeing their increased use in soccer, particularly internationally,” Wanich said. “For many players, it has become a part of their pregame ritual to get them mentally prepared for the match.”

If they appear at this summer’s tournament, Stein said he wouldn’t be surprised. “They’re really popular, any locker room I’ve been in, they’re around,” he said.

But Kovacs said players have betterm, healthier options:“I would rather see that athlete optimize the controllables that actually improve performance: sleep, nutrition, hydration, caffeine strategy if appropriate, breathing routines, warm-up structure, neuromuscular activation, and mental preparation.”

If an athlete feels they need smelling salts to get ready, Kovacs said it’s usually a sign the their preparation routine needs refining — not that more stimulation is the answer.

“In soccer, calm intensity is usually more valuable than uncontrolled arousal,” he said.