Let’s talk about poppers. The ever-expanding popularity of the decades-old party drug is all thanks to the magic of alkyl nitrites, a family of volatile chemicals that, much like many other, less accessible recreational drugs, leaves users dilated.

A key element to any party, whether in the club, tub, or bedroom, is letting loose. The circle of alkyl nitrites — which includes top popper amyl nitrite and encompasses its less-inhaled relatives cyclohexyl nitrite, isobutyl nitrite, and isopropyl nitrite — was originally adopted by disco freaks because of its relaxing mental and physical effects. Let’s focus on amyl nitrite: Inhaling its vapors causes a warm, tingling rush and briefly — the high hardly lasts any longer than 90 seconds — triggers mild euphoria, visual distortions, and the relaxation of sphincter-controlling muscles.

Inhaling the compound allows it to cascade into the bloodstream through the lungs. It quickly becomes a sanguine source of nitric oxide, a chemical that tells the body’s gateways and blood vessels to open up, causing blood pressure to drop dramatically. Alarmed, the heart reflexively beats faster to bring the pressure back up — hence, the thrumming pulse, flushed face and dizziness that tends to accompany the high. For clubbers in the 1970s, it was a small price to pay.

#TGIF getchya poppers for the wknd #theyloosenurbutthole

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In a 1977 article in the Wall Street Journal, one staff reporter describes a “trendy” East Side pair taking sniffs from a tiny glass vial at a chic nightclub, red-faced and giggling; in a San Francisco “in” disco, the frenetic dancing of young men is fueled by the same sweet-smelling fumes. The latter example winks at the gay community; the next year, Time Magazine elaborated, and explained that poppers weren’t just used by, but also directly marketed at homosexual men, who embraced the drug’s ability to ignite romance.

It wasn’t always so sexy. The first popper, amyl nitrite, was originally synthesized in 1844 and was co-opted some 20 years later by the Scottish doctor Sir Thomas Lauder Brunton, who used it to treat tightness-induced chest pain. Brunton, the first to take advantage of its muscle-relaxing abilities, paved the way for amyl nitrite’s use as a medical drug. In the U.S., it was prescribed to treat angina until 1960, when the FDA scrapped the prescription requirement and made it available over the counter. It wasn’t long before pharmacists noticed the “healthy young men buying the drug in bulk. By the time the prescription requirement was reinstated nine years later, a black market was already booming. Besides, it was already widely known that related — and illegal — members of the alkyl nitrite family could be found in VCR cleaners, nail polish removers, and room sprays.

Despite their cultural connotations, poppers aren’t named for the minor explosions they induce; medical-grade amyl nitrite used to take the form of tiny, glass-walled ampoules, which, enclosed within a bag of mesh, housed small amounts of the volatile liquid. Breaking the glass between the fingers caused the eponymous “pop”.

Amyl nitrite, the only member of the popper family still legal in the U.S., isn’t the most dangerous recreational drug, but it isn’t entirely safe, either. Overdosing has been known to cause vomiting, excessively low blood pressure, shortness of breath, and, in some cases, fainting; it’s also been linked to immunosuppression, a higher risk of HIV transmission, and the appearance of Kaposi’s sarcoma, a type of skin cancer associated with AIDS — although it’s still not entirely clear whether they result from the drug itself or the way it’s used.