Doctors have renewed their warnings over bath salts after a 34-year-old woman caught a flesh-eating infection following the substance’s injection into her arm at a party.

Injecting bath salts caused the life-threatening condition necrotizing fasciitis to spread through her upper body within days and led to surgeons having to cut away her arm, shoulder and breasts.

Banned in other countries, bath salts are still legal in the U.S.

The woman was examined by a team led by Dr. Russell Russo at Lousiana State University, after complaining of a painful and red forearm.

At first, the doctors thought the woman had a common skin infection and she was treated with antibiotics, which reduced her symptoms. However, she still had lingering pain at the site of a small red puncture wound.

The woman then admitted she had injected “bath salts” two days before and when she was re-examined doctors realized she had developed a flesh-eating infection.

The patient underwent emergency surgery as doctors battled to stop it spreading across her whole body.

“The infection moved so fast that pink, healthy tissue was literally dying before the surgeons’ eyes,” a university spokesman said.

“They had to keep removing tissue until they reached clear margins of healthy tissue to stop the progression of disease.

“By the time they were finished, the patient’s arm, shoulder, and collarbone had to be amputated, and a radical mastectomy performed.”

The woman survived and subsequently underwent skin grafting and rehabilitation.

“Bath salts” are man-made stimulant drugs that resemble scented bath powders and are still legal for use in water in the US

The doctors, writing in the latest edition of Orthopedics, are now warning other surgeons that they may see a rise in such cases.

“As <<bath salts>> gain popularity, medical centers of all disciplines must be prepared to identify not only the signs of intoxication, but the potential side effects including deadly necrotizing fasciitis,” Dr. Russell Russo said.

“Surgeons must be ready to diagnose and perform extensive debridements in association with general surgeons in some instances to save limbs, preserve function, and prevent death.”

“Bath salts” are man-made stimulant drugs that resemble scented bath powders and were banned in UK in 2010. However, they are still legal for use in water in the U.S.

The drugs, which go under names including Aura, Ivory Wave and Vanilla Sky – have dangerous side effects and users have needed several people to retrain them after arriving in emergency rooms.

“Despite the drug’s legal status, it must be treated as illicit, and one must be suspicious when examining a patient with this clinical history because the diagnosis of flesh-eating bacteria can masquerade as abscesses and cellulitis,” Dr. Russell Russo said.