About the time radium cosmetics went out of fashion, a new deadly beauty product hit the market: 2,4-Dinitrophenol, known as DNP.

DNP’s use as a diet pill took off in 1933, when the Journal of the American Medical Association published the discovery that the chemical could raise metabolism by up to fifty percent, causing a weight loss of up to two pounds a week with little to no effort. Reported as “not demonstrably harmful,” DNP quickly became the key ingredient in dozens of new weight-loss pills, only the latest in a tradition of dangerous treatments that had at various times contained amphetamines, snake oil, and even tapeworms.

By the 1930s, the diet industry was booming. While ideal silhouettes for both men and women have always been subject to change, women’s bodies in the ‘30s were shrinking faster than ever. When Hollywood’s Hays Code was finally enforced in 1934, even voluptuous figures could be viewed as obscene.

The Hays Code, also known as the Motion Picture Production Code, was a set of strict moral guidelines applied to the film industry’s major studios from 1930 until 1968. The Hays Code controlled or prohibited any content that could be deemed immoral, especially anything sexually suggestive. While it eliminated shared beds for married couples, first night scenes, heavy kissing, and sex work, it also inadvertently changed the way women looked–or wanted to look–across the nation. A curvaceous silhouette à la Mae West suggested licentiousness, and actresses became thinner to avoid the problem, changing the fashionable figure from the Victorian hourglass into the leaner frame that would remain in vogue for most of the twentieth century.

Women across the country followed suit, and the boyish figure popularized by the flappers of the ‘20s endured. In a time of economic uncertainty, their bodies were something they could control. Fad diets, amphetamines, laxatives, and cigarettes were as popular as ever, but nothing brought results like DNP. Within a year, at least 100,000 people were habitually taking pills containing DNP in the US alone. More than 1.2 million pills were distributed from a single clinic in San Francisco. It was cheap, available over the counter in most states, and very effective. It was so effective, in fact, that there was some concern that companies producing gym equipment and plus-sized clothing would go out of business.

DNP wasn’t a new substance. It had been used in pesticides, preservatives, and explosives for years. Highly flammable, it has eighty-one percent of the explosive strength of TNT, and it tastes like sulphur. It was its explosive properties that made it so effective for weight loss. Instead of converting food to fat or energy, DNP turns it into heat, “setting tiny internal fires” that can raise the body’s temperature high enough to cause brain damage and essentially cooking people from the inside out.

What could possibly go wrong? As it so happens, quite a bit. In addition to excessive sweating (often yellow) and shortness of breath, DNP can cause lesions, yellowing of the eyes, severe lethargy, cataracts, liver problems, damage to the brain and nervous system, loss of bone marrow, and heart failure. It should be no surprise that all those “tiny internal fires” make people overheat, sometimes fatally. DNP is incredibly dangerous, and deaths have been reported after even limited use.

Within three years of the initial report on its benefits, more than one hundred women in Los Angeles had lost all or part of their sight due to cataracts. A San Francisco doctor overdosed and quite literally cooked to death. Seven people were known to have died in the US as a direct result of taking DNP by 1936, but by then, it was used as a supplement around the world. In the Soviet Union, it was given to soldiers to keep them warm in the winter.

Even so, there was nothing prohibiting its sale in the United States. The Food and Drugs Act of 1906 didn’t apply because obesity wasn’t considered a medical condition. DNP continued to be sold under various names until the Federal Food, Drug, and Cosmetic Act was passed in 1938.

Under the new act, cosmetics and supplements had to be proven safe before they could be sold. Pills containing DNP were pulled from the shelves and makeup companies were finally regulated, effectively ending a long tradition of putting known toxic substances–including lead, arsenic, belladonna, mercury, and radium–into cosmetics.

But by then, the damage was done. DNP is widely regarded to be the most effective weight-loss drug of the twentieth century, but it is also the most lethal. Although it’s illegal to sell for consumption, its efficacy has ensured that people still find ways to buy it in spite of the near certainty of death.

Jessica Cale

Sources

Cutting WC, Mehrtens HG, and Tainter ML. Actions and uses of dinitrophenol: Promising metabolic applications. The Journal of the American Medical Association. 101 (3). 1933.

Haynes, Gavin. The Killer Weight Loss Drug DNP Is Still Claiming Young Lives. Vice. August 6th, 2018.

McKinney, Kelsey. Hollywood’s devastating gender divide, explained. Vox. January 26th, 2015.

Medicine: Again, Dinitrophenol. Time Magazine. June 29th, 1936.

McGillis, Eric. Rapid-onset hyperthermia and hypercapnea preceding rigor mortis and cardiopulmonary arrest in a DNP overdose. North American Congress of Clinical Toxicology Abstracts 2018.

Scutts, Joanna. The Depression Era’s Magic Bullet for Weight Loss. New Republic. May 27th, 2016.