Yesterday an acquaintance showed up on my doorstep (not booking an appointment) and wanted to know if Rhino “male enhancement” (erection producing) drugs, sold at gas stations and convenience stores, could show up in semen and if so, could she be harmed by swallowing potentially tainted semen during oral sex? This acquaintance was experiencing some disturbing symptoms after a recent sexual encounter, but they were so general, they could have been caused by a number of things.

She was also concerned because she said her partner broke out in horrible hives after taking these pills, but refused to stop using them.


This was the first time I’d been asked this question. I am not a medical doctor nor a pharmacist, and so I said so, along with “I don’t know but I’ll see if I can find out.”

What I did find out is that these products, marketed to men who experience uncertain erections, are not necessarily “all natural” or safe. They may be purchased on impulse, picked up on the way to a sexual encounter, without previous research or concern for product safety.

The Food and Drug Administration (FDA) has issued numerous warnings about Rhino products, and others. In a press release dated November 27, 2018, the FDA warned:

[Excerpt] The U.S. Food and Drug Administration is warning consumers not to purchase or use Rhino male enhancement products, due to a recent rise in reported health issues. Since 2007, the FDA has identified more than 25 products marketed with variations of the name “Rhino” that contained hidden drug ingredient(s).

These products continue to be sold at gas stations and convenience stores, as well as on websites such as eBay and Amazon. More recently, these unapproved products have been discovered in international mail shipments to the U.S. These products are often sold in single-serving package sizes. Rhino products include names such as Platinum Rhino 25000, Krazzy Rhino 25000 and Gold Rhino 25000.

The FDA has received reports of people experiencing chest pain, severe headaches and prolonged erections after taking a Rhino product that led to surgical intervention and hospitalization due to extreme drops in blood pressure.

“Over the past few years, the FDA has been combatting 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. Distributing unapproved drugs, disguised as supplements, places the U.S. public health at risk,” said Donald D. Ashley, director of the Office of Compliance in the FDA’s Center for Drug Evaluation and Research. “We remain vigilant in our efforts to protect the American public from the sale of these potentially dangerous products.” [End of excerpt]

These undisclosed ingredients may be hazardous to people who have diabetes, high blood pressure, high blood pressure, and heart disease. Here is another excerpt from the above press release:

[Excerpt] For example, the FDA has identified various Rhino products containing sildenafil and/or tadalafil, the active ingredients in the FDA-approved prescription drugs Viagra and Cialis, respectively. These undeclared ingredients are phosphodiesterase type-5 (PDE-5) inhibitors, which can be associated with significant safety issues and the risk of serious adverse events. For example, they may interact with nitrates found in some prescription drugs and may lower blood pressure to dangerous levels. People with diabetes, high blood pressure, high cholesterol or heart disease often take nitrates. [End of excerpt.]

I will note that diabetes affects blood circulation–poor blood flow can hinder erections–therefore diabetics with penises are likely to purchase these products.

Other FDA press releases on similar products may be found here.

Are these products found in semen, and swallowed by sexual partners?

I didn’t find much via a quick internet search. There seems to be very little research into the drugs that make it into semen (recreational and prescription) and even less research into potential adverse effects on a partner who swallows it or absorbs it (vaginally or anally). I didn’t come across any studies that specifically referenced the transport of Viagra or Rhino-type drugs into semen. Studies that did reference impacts of certain drugs were usually focused on reproductive outcomes and impacts on fetuses and embryos, or the potential impact of a drug on the quality and condition of sperm in the semen.

Drugs studied included HIV/AIDS anti-retrovirals, caffeine, and a few others. Here are screen shots of abstracts.

Here is the most recent study I found (in a quick search):

Pichini Drugs in semen 2005

From 1994:

Screen Shot 2020-02-09 at 9.52.55 AM

From 1986:

Hales et al. Cyclophosphamide seminal 1986.

And from 1984:

Screen Shot 2020-02-09 at 10.08.32 AM

Internet queries about drug exposures via semen ingestion were generally dismissed as being of little concern. Anecdotally, a variety of opinions were expressed by laypeople. Some cited testing positive for substances they’d never used, but a partner had. And some reported a difference in semen taste after that partner’s recreational or prescription drug use. (Many people say that tobacco users have notoriously foul-tasting semen). Medical professionals who sometimes answered such questions online didn’t have data, but even so they assumed this was a non-issue, a matter of little concern to the women (mostly) who were asking. These answers were based mostly on the assumption that the amount of any drug may be quite small by the time it shows up in semen.

However, this report of an almost fatal reaction after oral sex, demonstrates that some sexual partners may be hyper-sensitive or allergic to substances in semen (LiveScience, 2019). [Note: no mention of this incident in Snopes.]

Allergic reaction to semen 2019

The acquaintance who showed up on my doorstop may be right about the source of her symptoms. It’s in the realm of possibility, but I am not sure about probability. However, I also advised her to get tested for a range of STIs, as the behaviors and conditions she reported seemed high-risk, and her partner did not seem to disclose his behaviors or statuses honestly. He has multiple partners. She didn’t use a condom during oral sex. She may not have wanted to do this, or she may have been discouraged from doing so.

I wish I could have offered more help to this person, even though she is not a client, and I tried to not treat her as one. But her questions about this matter caused me to think through some of my own assumptions about safety and particularly about drugs that might contaminate semen and might affect a sex partner.

People with penises who are dissatisfied with the reliability or quality of their erections should resist the lure of over-the-counter “fixes” and consult a medical professional to (1) rule out other conditions (like diabetes); (2) to get testosterone tests and other evaulations, and (3) obtain prescriptions, if warranted. After that they can see a sexuality counselor or therapist to get education, learn sexual strategies, and find help for any non-medical aspects of sexual dysfunction (such as worry). If they take an over the counter pill, they should see a doctor and report adverse effects to the FDA.

If any reader here has further study citations to offer, I’d appreciate hearing about them.