What are the STI risks specific to fellatio compared with cunnilingus and anilingus?

1. Fellatio: the strongest oral route for gonorrhoea and certain bacterial STIs

The clearest and most consistent epidemiologic signal across reviews and public-health summaries is that giving and receiving fellatio is strongly associated with pharyngeal gonorrhoea and can transmit Chlamydia trachomatis; multiple studies report an association between receptive and insertive fellatio and these infections ^[1][3][2]. Case reports and surveillance link fellatio to coincident acquisition of Neisseria gonorrhoeae and even, rarely, HIV from oral exposure—though HIV risk from oral sex is much lower than for vaginal/anal routes ^[4][5]. Oral mucosal trauma during fellatio may further increase susceptibility to bacterial and viral transfer ^[6].

2. Cunnilingus: viral risks and a different bacterial picture

Cunnilingus is less commonly implicated than fellatio in pharyngeal gonorrhoea but shows clearer links to mucocutaneous viral infections such as herpes simplex (transmission to or from the mouth/throat) and human papillomavirus; some studies report receptive cunnilingus associated with herpes acquisition ^[1][7]. Evidence for bacterial transmission from vagina to mouth—while possible—is less robust and less often the focus of screening recommendations, so clinicians are less likely to routinely test oral sites for many bacteria after exclusive cunnilingus exposures ^[2][3].

3. Anilingus: hepatitis and enteric pathogens drive unique risks

Oral-anal contact (anilingus or “rimming”) presents distinctive hazards because the anus and rectum commonly harbor enteric bacteria and viruses; public health agencies specifically note that anilingus can transmit hepatitis A and B and can spread intestinal infections and parasites ^[8][4][9]. While fewer studies quantify comparative STI incidence for anilingus versus other oral practices, guidance consistently flags viral hepatitis and enteric pathogens as chief concerns for oral-anal exposure ^[4][9].

4. Common threads: syphilis, HPV, HIV and overall lower relative HIV risk

Syphilis has been documented across all oral practices and therefore should be considered a cross-cutting risk for fellatio, cunnilingus, and anilingus alike ^[1]. HPV can be transmitted by oral sex and is a concern because of oropharyngeal cancers, though the prevalence and detectability vary ^[7]. Public-health reviews and the CDC emphasize that while HIV transmission via oral sex is possible, it is generally much lower than with penetrative sex—risk is context-dependent (presence of bleeding, high viral load, concomitant STIs) and not zero ^[1][5][10].

5. Prevention, screening and where practice diverges from evidence

Barriers (condoms for fellatio; dental dams or cut-open condoms/plastic wrap for cunnilingus/anilingus), vaccination (hepatitis A/B, HPV), regular testing targeted by sexual behaviour, and prompt treatment of symptomatic partners are the evidence-based ways to reduce risk; public-health materials and student-health pages convey these prevention messages ^[11][7][2]. However, testing systems and clinical practice often prioritize urethral and genital screening; throat and rectal screening patterns lag even when epidemiology suggests benefit—an implementation gap noted in reviews ^[1][6].

6. Limits in the literature, competing narratives and hidden agendas

The literature is uneven: bacterial infections like gonorrhoea have clear pharyngeal data, while other STI routes (HPV, syphilis, less common pathogens) are less well-characterized and under-studied, producing sometimes emphatic public advice built on limited evidence ^[1][6]. Sexual-health advocates and clinical sites emphasize harm reduction and practical prevention, while some commercial or sensational sources overstate numerical risks without robust denominators; readers should weigh primary public-health reviews (CDC, peer-reviewed syntheses) higher than single unreferenced web posts ^[8][1].