Can Drugs and Medications Be Transferred Through Semen?

Questions from readers about whether drugs and medications can be transferred to sexual partners via semen have been coming in on a surprisingly regular basis for almost ten years. The very first question read as follows, but there have been multiple variations on it over the years: 

“Can medications that men take regularly (like blood pressure, cholesterol, or diabetes meds) be passed through their seminal fluid to their oral sex partner? Many sex workers prefer to perform oral sex without a condom (bareback) and they often make the decision to swallow rather than spit. If medication can be passed like this, are these girls at any risk?”

When this question was first answered on the blog, we knew that medications that men take can show up in their semen, albeit in incredibly small amounts. This makes sense because we’ve long know that drugs can appear in various body fluids (e.g., blood, urine), hence why body fluids are typically used for drug testing. However, in terms of the amount of drugs/medications found in these different bodily fluids, “seminal fluid chemical concentrations are typically similar to or lower than blood concentrations” [1]. 

What we didn’t know when this question was first answered was whether this small amount of chemicals within semen was something that could actually absorbed by men’s sexual partners, and if there were any potential negative effects as a result. It was assumed that because the amount of chemicals present in semen was so small that there wouldn’t be any meaningful chemical transfer. However, there are a few case studies that have since emerged that suggest otherwise. 

For example, one study presents a case of a woman who suffered an allergic reaction after engaging in penetrative and oral intercourse with a male partner. After having sex with a male partner that included “vaginal and oral sex with oral ejaculation,” she had to go to the emergency room because she was experiencing full-body hives, shortness of breath, and “abundant vomiting” [2]. Of course, one potential cause for an anaphylactic reaction from ingesting semen may be because a person has a semen allergy, which is where an individual is allergic to the specific proteins in semen. Symptoms may include surface-level irritation where semen has come into contact with skin, but it may also lead to allergic-reactions, including anaphylaxis. 

However, it would be unusual for a semen allergy to be the cause for the patient described above, given that she had never previously had this kind of reaction before from ingesting semen. A closer look at this patient’s medical history revealed that she has a penicillin allergy, and had experienced similar symptoms as a child after taking amoxicillin. Now, what does this have to do with swallowing semen? Well, it turns out that her sexual partner was prescribed an antibiotic that contained amoxicillin, and he took one of his doses four hours before they had sex. The doctors concluded that this woman’s allergic reaction may therefore have been triggered by the small amount of amoxicillin that was in the semen she swallowed due to her partner being on antibiotics [2]. 

Are these effects specific to orally ingesting semen? A different study tells us that this is not necessarily the case [3]. A second report details a 46 year old woman who went to the emergency room with a litany of allergic symptoms, including dizziness, sweating, and itchy hands and feet. Like our first example, she too had a penicillin allergy that was diagnosed when she was a child, and started presenting her symptoms only 1-2 hours after having sex with her husband. Her husband was on his fifth day of an antibiotic treatment that contained nafcillin, which is in the penicillin family. However, unlike the first case, this patient did not ingest her husband’s semen; their sexual interaction involved ejaculation into the vagina without the use of a condom. Thus, it also appears possible for antibiotics to be transmitted through semen during vaginal intercourse, although it is believed that this kind of reaction is likely to be quite rare [3]. 

These studies suggest that drugs and medications can potentially be transmitted to sexual partners through semen, and that this can happen through both oral and vaginal sex. But are there implications of this beyond possible allergic reactions? Another study recently investigated the possibility for drugs to be transferred through semen based on a few cases where female athletes failed doping tests. These women claimed that they had not ingested banned substances, but that they engaged in recent sexual intercourse with men who had [4]. This study (which involved chemical analyses of semen samples) suggested that drugs might be transferrable through semen because there are trace amounts of urine in seminal fluid, which may carry a higher concentration of the substance that could be absorbed. However, this study leaves a lot of unanswered questions, including how long drugs would remain detectable in one’s system following possible semen transfer. 

Overall, several small studies published since this question was originally answered point to the possibility that drugs and medications can potentially be transferred to sexual partners through semen. However, it seems that the risk of negative effects are quite low unless someone has a specific drug/medicinal allergy or they are subject to extremely-sensitive drug tests soon after having unprotected sex. 

If you have a sex question of your own, record a voicemail at speakpipe.com/sexandpsychology to have it answered on the blog or the podcast. 

References:

[1] Klemmt, L., & Scialli, A. R. (2005). The transport of chemicals in semen. Birth Defects Research Part B: Developmental and Reproductive Toxicology, 74(2), 119-131.

[2] Caballero, N. G., Almenara, S., Terol, A. T., & Parte, J. F. H. de la. (2019). Anaphylaxis probably induced by transfer of amoxicillin via oral sex. BMJ Case Reports CP, 12(3), e227398. https://doi.org/10.1136/bcr-2018-227398

[3] Marchitto, M. C., Petrone, D., & Gradon, J. D. (2019). Almost killed by love: A cautionary coital tale. The American Journal of Medicine, 132(8), e650–e651. https://doi.org/10.1016/j.amjmed.2019.03.008

[4] Handelsman, D. J., Bacha, F., DeBono, M., Sleiman, S., & Janu, M. R. (2022). Sexually transmitted doping: The impact of urine contamination of semen. Drug Testing and Analysis, 14(9), 1623–1628. https://doi.org/10.1002/dta.3331

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