Rugby’s authorities have no immediate plans to follow American football’s NFL in banning ‘smelling salts’ over concerns they may mask concussion symptoms.

Smelling salts – a pungent mix of ammonia, water and ethanol – are marketed as improving mental alertness or boosting energy.

One study suggested that by irritating the nose and lungs, they stimulate a sharp intake of breath and a short-term rush of oxygen to the brain.

However, in a memo to their teams, obtained by the Associated Press,, external the NFL warned smelling salts also “have the potential to mask certain neurological signs and symptoms, including some potential signs of concussion”.

Their use is common in high-level rugby dressing rooms.

During half-time of the first British and Irish Lions’ Test against Australia last month, Lions flanker Tadhg Beirne was shown inhaling smelling salts as the rest of the team huddled up.

Video of his use of smelling salts, and team-mate Jack Conan’s reaction, were used on the team’s social media., external

Team-mate Ellis Genge has previously used them directly before England matches, while Premier League footballers have been pictured apparently using them on the pitch.