STIs spread through vaginal, anal, or oral sex and genital skin contact; several also spread through blood and from mother to infant. Many infections are asymptomatic, so absence of symptoms does not mean absence of infection — screening, partner treatment, and prevention are central nursing tasks. Having one STI (especially ulcers or inflammation) increases the risk of acquiring and transmitting HIV.

Syphilis stages

• Primary (about 3 weeks after exposure): painless, firm, clean-based ulcer (chancre) at the site of entry, heals on its own
• Secondary (weeks to months): rash including palms and soles, condylomata lata (moist, flat wart-like lesions), fever, lymphadenopathy, patchy hair loss
• Latent: no symptoms, positive blood tests (early latent = infection within the past year)
• Tertiary (years later): gummas (destructive granulomas), cardiovascular syphilis (aortitis)
• Neurosyphilis, ocular syphilis, and otosyphilis can occur at any stage — vision or hearing changes need urgent evaluation

Sexual history — the "5 Ps": Partners, Practices, Protection from STIs, Past STI history, Pregnancy intention; ask in a private, nonjudgmental way using inclusive language.

Findings

• Discharge (urethral, vaginal, rectal), dysuria, intermenstrual or postcoital bleeding, pelvic pain
• Genital ulcers: painful multiple vesicles/ulcers → herpes; painless single indurated ulcer → primary syphilis
• Warty growths (HPV); rash on palms and soles (secondary syphilis)
• Lymphadenopathy, fever, sore throat, rash (acute HIV)
• Prodrome before herpes recurrence: tingling, itching, or burning at the site hours to days before lesions appear
• Signs of sexual violence or coercion — assess safety

• Chlamydia and gonorrhea: NAAT of vaginal swab (preferred for women), urine, or pharyngeal/rectal swabs by exposure site; gonorrhea culture with susceptibility if treatment fails
• Syphilis: nontreponemal test (RPR or VDRL) — titers track activity and treatment response; treponemal test (e.g., FTA-ABS, TP-PA, EIA) — stays positive for life; many labs screen with a treponemal test first ("reverse sequence"); darkfield or PCR of lesions
• Herpes: PCR of lesion fluid (preferred) or culture; type-specific serology in selected cases
• HIV: antigen/antibody (4th-generation) test, with HIV RNA testing when acute infection is suspected
• Hepatitis B: HBsAg, anti-HBs, anti-HBc
• Screening recommendations (US, summary)
  • Chlamydia and gonorrhea: sexually active women under 25 yearly, older women at increased risk
  • HIV: at least once for everyone 13–64 (CDC) / 15–65 (USPSTF), more often with risk; all pregnant women
  • Pregnancy: HIV, syphilis, hepatitis B at the first prenatal visit; chlamydia and gonorrhea for those under 25 or at risk; syphilis testing is repeated in the third trimester (about 28 weeks) and at delivery for those at risk or in high-prevalence areas — with rising congenital syphilis, many US guidelines now recommend repeat testing for all
• Anyone diagnosed with one STI should be tested for others (HIV and syphilis)

Treatment (CDC 2021 STI Treatment Guidelines and later updates)

Prevention

• Vaccines: HPV (routine 11–12, catch-up through 26; 2 doses if started at 9–14, 3 doses if started at 15 or older or immunocompromised), hepatitis B (all adults 19–59; older adults with risk), hepatitis A for those at risk
• HIV PrEP: daily oral tenofovir disoproxil fumarate–emtricitabine (for all at risk, including those with receptive vaginal sex); tenofovir alafenamide–emtricitabine (not studied for receptive vaginal sex); long-acting injectable cabotegravir every 2 months; lenacapavir injection every 6 months (FDA-approved June 2025, recommended by CDC in September 2025). Confirm HIV-negative before starting and before each injection — PrEP in undiagnosed HIV causes drug resistance; kidney function with tenofovir; injectables cause injection-site reactions or nodules and leave drug levels for months after stopping
• HIV PEP: start as soon as possible and within 72 hours of exposure; 28 days of ART
• Doxycycline post-exposure prophylaxis (doxy-PEP) (CDC 2024): doxycycline 200 mg once within 72 hours after oral, vaginal, or anal sex (no more than 200 mg in 24 hours); recommended for gay, bisexual, and other men who have sex with men and transgender women with a bacterial STI in the past 12 months. Not recommended for cisgender women (insufficient evidence)
• Expedited partner therapy (EPT) — giving medication or a prescription for the partner of a client with chlamydia, gonorrhea, or trichomoniasis without a partner exam, where legally permitted
• Chlamydia, gonorrhea, syphilis, and HIV are reportable to public health

Drug safety

Listed in priority order.

1. Recognize complicated or systemic infection — disseminated gonorrhea (fever, joint pain, skin pustules), neurosyphilis or ocular syphilis (vision loss, hearing loss, confusion), PID, and acute HIV → urgent referral
2. Administer treatment safely — verify allergies; benzathine penicillin IM only, observe for anaphylaxis; watch for Jarisch–Herxheimer reaction
3. Prevent perinatal transmission — screen in pregnancy; ART for pregnant clients with HIV; hepatitis B vaccine and HBIG for exposed newborns; erythromycin 0.5% ophthalmic ointment to newborns' eyes; cesarean birth for active genital herpes lesions or prodrome at labor
4. Standard precautions; glove for lesion contact; herpes lesions — avoid touching and wash hands
5. Partner notification and EPT — explain that partners from the prior 60 days (chlamydia, gonorrhea) or per syphilis stage need testing and treatment
6. Counseling — risk reduction, condoms, vaccination, PrEP/PEP, doxy-PEP when eligible
7. Therapeutic communication — privacy, confidentiality, nonjudgmental tone; give accurate information when clients worry about fertility (untreated chlamydia can lead to PID and infertility; prompt treatment lowers this risk)
8. Follow-up — retesting at 3 months (chlamydia, gonorrhea, trichomoniasis); syphilis titers at 6 and 12 months

• Take all medication; no sex for 7 days after single-dose therapy or until a 7-day course is finished, symptoms have resolved, and partners are treated
• Being treated does not make you immune — reinfection is common; retest in 3 months
• Condoms, used correctly every time, greatly reduce most STIs; they reduce but do not fully prevent HPV and herpes (skin contact outside the condom)
• Hormonal contraception does not protect against STIs
• A partner without symptoms can still be infected — ask partners to get tested
• Herpes: no cure; lesions are most contagious, but virus can spread without symptoms; avoid sex from prodrome until lesions heal; daily suppressive therapy reduces spread; keep lesions clean and dry, wear loose cotton clothing, sitz baths or pouring warm water over the area while voiding eases pain; inform your prenatal provider
• Genital warts: do not use over-the-counter wart removers on genital skin; warts can recur; the virus may remain even after lesions are removed
• Syphilis: flu-like symptoms after the injection are expected (Jarisch–Herxheimer) — pregnant clients should report contractions or reduced fetal movement; return for blood tests
• HIV: take ART every day; U=U; PrEP and PEP are available — know the 72-hour PEP window
• Hepatitis B: get vaccinated; do not share razors or toothbrushes
• Seek testing for any new sores, discharge, or rash

• Many STIs are asymptomatic — screen sexually active women under 25 yearly for chlamydia and gonorrhea
• Chlamydia → doxycycline 7 days (azithromycin in pregnancy); gonorrhea → ceftriaxone 500 mg IM once
• Syphilis: primary = painless chancre; secondary = rash on palms and soles, condylomata lata; treat with benzathine penicillin G IM (never IV); pregnancy = penicillin only
• Jarisch–Herxheimer: fever and myalgia within 24 hours of syphilis treatment
• Herpes: painful vesicles, latent in ganglia, prodrome tingling; acyclovir/valacyclovir; cesarean for lesions at labor
• Genital warts = HPV 6 and 11; treat lesions, not the virus
• Treat partners (60 days); no sex until treatment complete and partners treated; retest in 3 months
• Doxy-PEP: 200 mg within 72 hours, for MSM and transgender women with a recent bacterial STI — not for cisgender women
• HIV PEP within 72 hours for 28 days; PrEP options include oral daily, cabotegravir every 2 months, lenacapavir every 6 months
• U=U; newborn eye prophylaxis with erythromycin
• Hormonal contraception does not prevent STIs; condoms reduce risk