Aspiring Navy SEALs are using Viagra to self-medicate when they start coughing up blood during qualifying drills. They say it works — but at a price.

• In February, a Navy SEAL recruit died after the intense portion of training known as Hell Week.
• He reportedly used illicit Viagra to offset a buildup of fluid in the lungs from strenuous swimming.

The Navy SEALs' infamously difficult training course is so brutal, some recruits are turning to drugs to make it through, including off-label use of Viagra, reports the New York Times.

Basic Underwater Demolition/SEAL, or BUD/S for short, is notorious for having one of the highest rates of failure in the US military, a grueling mental and physical ordeal that only the most resilient enrollees can withstand. Only 15-30% of recruits who start the program will complete it, Insider's Stavros Atlamazoglou previously reported.

One portion of training, known as "Hell Week," occurs early on in training but involves near-constant cold, damp, and physical exertion, combined with sleep deprivation.

The program has attracted controversy for recent deaths, and the discovery that recruits were using performance-enhancing drugs to face the challenges of SEAL training.

In February, one recruit died and another was hospitalized after Hell Week. US Navy Seaman Kyle Mullen died February 4, and his death was officially listed as bacterial pneumonia — he had been coughing up blood for days, the Times reported.

During extensive, strenuous swimming in frigid waters, participants in SEAL training may develop a dangerous condition called swimming-induced pulmonary edema, or SIPE, in which fluid builds up in the lungs. A common symptom is coughing up bloody fluid.

One potential treatment for SIPE is sildenafil, better known as Viagra, which is typically used to treat erectile dysfunction.

Mullen had been taking Viagra, against Navy regulations, on the advice of his fellow recruits to manage symptoms of SIPE and stay in the program, his mother told the Times. He recovered enough to keep training, but his condition worsened as the program progressed, according to the Times. Mullen started to fall behind, collapsed, and needed oxygen from nearby medics, but continued through the training until the conclusion of Hell Week, the Times reported.

He completed a medical check, but after medical staff had left, he coughed up enough bloody fluid to fill a Gatorade bottle, according to the Times. Hours later, new recruits called 911 for a medical emergency and medics arrived to find Mullen unresponsive and without a pulse.

Afterward, the Navy found syringes and performance enhancing drugs in Mullen's car, and a subsequent investigation identified 40 recruits who either tested positive or admitted to illicit substance used, the Times reported.

While Mullen's death wasn't tied directly to drugs, it prompted more scrutiny and adjustments to the BUD/S program, removing some of the harsher elements, according to the Times.

And over time, the drugs can add to the stress on sailors' vital organs, including their hearts and livers, Dr. Matthew Fedoruk, the chief science officer of the United States Anti-Doping Agency, told the Times. It could also make it harder for drug-free recruits to compete, raising the stakes even higher for all trainees to push through even more exhaustion and injury.

"It makes it that much harder for the people doing the right thing to shine," he said.