The Food and Drug Administration has issued a warning about a black-market male enhancement pill that causes prolonged erections.

The dubious drug is sold under variations of the name “Rhino” at gas stations and convenience stores, usually in single-dose packets.

But it contains potentially dangerous ingredients, including some not listed on the package. Some of the hidden ingredients are similar to those found in prescription erectile dysfunction pills Viagra and Cialis.

The FDA said it’s received reports of people who’ve experienced chest pain, severe headaches and extended erections after taking “Rhino” pills.

Some cases resulted in “surgical intervention and hospitalization due to extreme drops in blood pressure,” the agency said.

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More than 25 different “Rhino” products — sold under names like “Platinum Rhino 25000,” “Krazzy Rhino 25000” and “Gold Rhino 25000” — have been identified as containing secret ingredients.

The pills are also sold on eBay and Amazon.

The hidden ingredients are phosphodiesterase type-5 (PDE-5) inhibitors, which could interact with nitrates in prescription drugs used to treat people with diabetes, high blood pressure, high cholesterol or heart disease, the FDA warned.

“Over the past few years, the FDA has been combating the retail sale of male enhancement drug products that are frequently misrepresented as dietary supplements and that contain hidden and potentially harmful active drug ingredients,” said Donald D. Ashley, director of the Office of Compliance in the FDA’s Center for Drug Evaluation and Research, in a statement.

Last month, a South Korean national believed to be living in the Los Angeles area illegally was busted for smuggling drugs in order to produce the shady male enhancement pills.

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Nam Hyun Lee, 60, had been illegally importing Tadalafil and Sildenafil Citrate — active ingredients found in Cialis and Viagra — from Hong Kong and China and using them to create “non-prescription herbal male sexual enhancement products,” according to the Department of Justice.

The pills were sold under names like “Rhino,” “Orgazen,” “Black Panther,” “libigrow,” “Black Stallion” and “Black Mamba.”

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