What to expect in this article
After a busy day that ended in a bar or a party to celebrate a new business deal, you woke up in an unfamiliar bed with someone you barely knew. A one-night stand. This is how it works. Several drinks or a naughty surprise from your friends has brought you to this point, and it seems you had unprotected intercourse with a person of unknown STD status.
Worrisome, right? Here’s everything you need to know about one-night stands and sexually transmitted diseases (STDs).
You will learn:
- What the risk is of acquiring these STDs from a one-night stand with and without protection:
- HIV
- Herpes
- Gonorrhea
- Chlamydia
- Syphilis
- HPV
- Myths about preventing STDs right after unprotected sex
- What is effective against most STDs: post-exposure prophylaxis
- How chlamydia, gonorrhea, and trichomoniasis can be eradicated
- How to prevent HIV (it’s urgent!)
- How syphilis can be eradicated
- Hepatitis B and HPV can be prevented with vaccines
- The bad news about herpes
The risk of acquiring specific STDs from one instance of unprotected sex
| Disease | Vaginal sex | Anal sex |
|---|---|---|
| HIV | 0.05–0.1% or 4 per 10,000 sexual acts | Receptive sex 1.4% or 138 per 10,000 |
| Insertive sex 0.06% - 0,16% or 11 per 10,000 sexual acts | ||
| Herpes | 0.3-0.7% | No exact data available |
| Gonorrhea | 20% | Receptive sex: 84% |
| Insertive sex: 2% | ||
| Chlamydia | 4.5% | 32% |
| Syphilis | 51-64% | 30-60% |
| HPV | 4% per 100 person-months | Receptive sex: 33.7%-85.7% |
| Insertive sex: 0.8%-14.2% |
The risk of acquiring specific STDs from one instance of protected homosexual sex. 6,7
| Disease | Risk per Protected Act |
|---|---|
| HIV | Very low (0.04%-0.18%) |
| Herpes | Low-Moderate if the lesions are covered by a condom |
| High if the lesions are not covered | |
| Gonorrhea | Low |
| Chlamydia | Low |
| Syphilis | Low-Moderate if the ulcer is covered by a condom |
| High if the ulcer is not covered | |
| HPV | Low-Moderate if the infective surface is covered by a condom |
| High if the infective surface is not covered |
Condoms are highly effective in protecting against HIV, gonorrhea, and chlamydia (STDs that are transmitted through body fluids). Condoms are somewhat protective against HPV, syphilis, and herpes, which can be transmitted through skin-to-skin contact. If you want to practice “safe sex”, we do encourage you to use condoms.
Measures you might think are helpful immediately after unprotected sex
Unfortunately, doing these things does not prevent STDs:
- Washing the penis
- Douching
- Urinating after intercourse
These will help prevent urinary tract infections only. There is no evidence suggesting that cleaning your genitals with alcohol can be useful in preventing STDs. Moreover, overly active rubbing may irritate your skin and increase the risk of STD acquisition.
Measures that are helpful
For most STDs, post-exposure prophylaxis is available. Healthcare providers use certain algorithms for risk assessment and selection of those in need of prophylaxis. For most STDs, they recommend waiting for test results or symptom development. However, if you are extremely concerned, it is possible to start the prophylaxis right after the exposure. The duration of prophylaxis differs from one STD to another. Mostly drugs are well tolerated or have bearable side effects.
Chlamydia, gonorrhea, and trichomoniasis can be prevented with a single recommended regimen
For chlamydia, gonorrhea, and trichomoniasis prevention, this approved antimicrobial drug combination is used:
A single dose of ceftriaxone (intramuscular injection 250 mg) plus a single dose of azithromycin (1g by mouth) plus a single dose of metronidazole (2g by mouth) OR a single dose of tinidazole (2g by mouth).8 Ceftriaxone is used for gonorrhea prophylaxis, whereas azithromycin is effective against chlamydia. Metronidazole or tinidazole is used for trichomoniasis treatment. Metronidazole has common side effects, such as nausea, vomiting, and diarrhea. Ceftriaxone can be effective against syphilis in the incubation phase. 9
What healthcare providers suggest for chlamydia, gonorrhea, and trichomoniasis eradication
Get tested two weeks after the exposure and start the treatment only if you tested positive. Antibiotic misuse can lead to bacteria being resistant to antibiotics.
Postexposure prophylaxis for HIV must begin within 72 hours after exposure
HIV postexposure prophylaxis (PEP) is time-sensitive. It must be administered within 72 hours of the exposure. And ideally, it should be administered within 4 hours after the exposure. PEP is administered for 28 days. You should take it once or twice per day. PEP is well tolerated and side effects (e.g., nausea and kidney and bone toxicity) are bearable and treatable. A combination of Truvada and raltegravir or dolutegravir is usually prescribed. Contact your healthcare provider for a risk assessment and to discuss therapy.10
Who should have PEP
Men are at high risk and should have PEP if they engaged in any of the following:
- Unprotected receptive anal intercourse
- Unprotected insertive anal intercourse
- Unprotected insertive vaginal intercourse
If their skin or mucosal lesions were exposed to infected blood or body fluids containing blood.
Syphilis can be easily eradicated
Syphilis can be eradicated with just one dose of benzathine penicillin G (2.4 million units) given by intramuscular injection within three months after exposure.11 This has been shown to be 95% effective. The same treatment is given (one dose) if you contracted syphilis within the last year. If you are not sure about your previous syphilis status (you didn’t test for syphilis more than a year ago), you should have three prophylactic doses within 21–27 days (each for 7–9 days). A Jarisch–Herxheimer reaction can develop in syphilis-positive people as a side effect of treatment. You may develop fever, joint pain, headaches, and a fast heartbeat. This reaction is due to the death of bacteria and lasts for 24 hours.12
Healthcare providers suggest waiting to be certain about the diagnosis of syphilis
Common practice suggests getting tested for syphilis first (serological tests two to four weeks after exposure) and initiating the treatment after positive results. Improper treatment can mask syphilis manifestations, resulting in complications several years later.
There is no post-exposure regimen for herpes
Unfortunately, effective post-exposure prophylaxis for Herpes does not exist
Vaccine can be used for hepatitis B and HPV post-exposure prophylaxis
You can get hepatitis B vaccine if you have not been vaccinated and do not know your partner’s hepatitis B status. You need only the vaccine—hepatitis B immune globulin (HBIG) is not administered. You should get the first dose after the possible exposure, a second dose one or two months later, and a third dose four to six months after the initial dose. If you know that your partner is HBsAg-positive (i.e., hepatitis B–positive), you should also get HBIG. You need only one dose if you have previously been vaccinated but didn’t test for hepatitis B afterward.8
HPV vaccine has age limitations
Heterosexual males should not get HPV vaccine over the age of 21. Men who have sex with men should not get it if they are older than 26. You should get the first dose (if you weren’t vaccinated or were vaccinated improperly) after the possible exposure, a second dose after one or two months, and subsequently a third dose.
References
1. HIV TRANSMISSION RISK: A SUMMARY OF THE EVIDENCE.
2. HIV Risk Behaviors | HIV Risk and Prevention Estimates | HIV Risk and Prevention
3. Klein H, Kaplan RL. Condom use attitudes and HIV risk among American MSM seeking partners for unprotected sex via the internet. NCBI
4. Kirkcaldy RD, Weston EA, Segurado AC, Hughes G. Epidemiology of gonorrhoea: a global perspective. 1906. doi:10.1071/SH19061
5. Condom Fact Sheet for Public Health Personnel | CDC.
6. Usaid. USAID - Condom Fact Sheet.; 2015.
7. Condom Use by Adolescents | American Academy of Pediatrics.
8. Sexual Assault and Abuse and STDs - 2015 STD Treatment Guidelines. CDC
9. Sachs CJ, Thomas B. Sexual Assault Infectious Disease Prophylaxis. StatPearls Publishing;NCBI
10. Evaluation and management of adult and adolescent sexual assault victims - UpToDate.
11. Klausner JD. The great imitator revealed: syphilis. NCBI
12. Syphilis Treatment & Management: Approach Considerations, Antibiotic Therapy, Surgical Care. Emedicine
