US Pharm. 2020;45(4):10-12.

 Sexually transmitted diseases (STDs) are infections that pass from one person to another through sexual contact. They are a major public health problem. STDs are frequently asymptomatic and can lead to various complications. As a result, it is important to identify and treat infected persons before they develop complications and transmit the disease to others.1

Most STDs affect both men and women, but in many cases the health problems they cause are more severe for female patients. If a pregnant woman has an STD, it can present severe health risks for the baby.2 Antibiotics can treat STDs caused by bacteria or parasites. There is no cure for STDs caused by viruses, but medication can mitigate the symptoms and keep the disease under control.2

The causes of STDs include bacteria, parasites, and viruses. There are more than 20 types of STDs, including chlamydia, genital herpes, gonorrhea, some forms of hepatitis, HIV, human papilloma virus (HPV), syphilis, and trichomoniasis.1 In 2015, the CDC provided specific recommendations and guidelines about the screening and treatment of STDs.1

The correct usage of latex condoms greatly reduces, but does not completely eliminate, the risk of catching or spreading STDs. The most reliable way to avoid infection is to abstain from unprotected sex.2

Screening and Diagnosis

The diagnosis and management of STDs are based upon the specific disease symptoms. These include vaginal discharge, urethral discharge, ulcerative and nonulcerative genital diseases, and pelvic pain. However, many STDs are asymptomatic, increasing the risk of sustained transmissions.2

Problems associated with untreated sexually transmitted infections (STIs) include upper genital tract infections, infertility, chronic pelvic pain, cervical cancer, and chronic infection involving hepatitis viruses and HIV. Thus, in most cases, screening is an important approach to identify and treat infected patients who would otherwise go undetected. Among all STDs, the screening for chlamydia has been the most extensively studied. 


The prevention of STDs must always be given high priority. The major strategies to STD prevention are as follows2: accurate risk assessment to avoid STDs; vaccination of individuals at risk, when possible; identification of asymptomatic and symptomatic persons with STIs; effective diagnosis and treatment along with follow-up; and education and counseling of sex partners.

Sexually Transmitted Infections

Chlamydia and Gonorrhea: In the United States, Chlamydia trachomatis and Neisseria gonococcus are the two most commonly reported communicable diseases. Screening women for these STDs will reduce the risk of infection to their reproductive systems. In men, who have a lower risk of long-term problems, the main purpose for screening and treatment would be to reduce the likelihood of reinfection of partners and to reduce overall infection transmission.3

Syphilis: Syphilis can lead to serious long-term problems, including cardiac and neurologic manifestations, which are prevented by treatment in the minimally symptomatic early stages of disease. Syphilis is associated with an increased risk for HIV transmission and acquisition. In the U.S., the majority of all primary and secondary syphilis cases occur among men who have sex with men (MSM), many of whom are HIV-infected.3

Trichomonas: Trichomonas vaginalis infection is often asymptomatic and has been associated with adverse pregnancy outcomes in healthy and HIV-infected women. The prevalence of trichomoniasis appears to increase with age and is up to twice as high in HIV-infected women. It increases the risk of pelvic inflammatory disease (PID) in females.4

HPV: HPV causes virtually all cancers of the cervix and is associated with oropharyngeal and anal cancer. In the U.S., guidelines issued by various professional organizations strongly recommend screening for cervical cancer. Cervical cancer screening policies in other countries differ by starting age, stopping age, and frequency.2 There are no screening tests for HPV-associated oropharyngeal cancers. HPV vaccination can prevent HPV infection and its sequelae.2

Mycoplasma genitalium: Routine screening for M genitalium is not recommended. It is a recognized cause of nongonococcal urethritis in men and has been associated with cervicitis and PID in women. However, the benefits of screening and treatment in asymptomatic persons are unclear.2,5

Herpes Simplex Virus: Routine screening for genital herpes simplex virus (HSV) infections is not recommended. However, performing type-specific serologic testing for HSV can be useful on an individual basis to counsel couples on their risk for HSV transmission, particularly during pregnancy. The majority of infections are transmitted from individuals unaware of their infection or during asymptomatic periods between outbreaks. However, treatment is generally reserved for those with symptomatic disease.1,2

HIV and Hepatitis Viruses: Untreated HIV infection and chronic hepatitis B and C viruses (HBV and HCV) can result in substantial excess morbidity and mortality, and contribute to further transmission of these infections. These infections can be transmitted sexually as well as through other routes. Screening is recommended for broader populations than just those at risk of sexual acquisition. The risk is higher in those with multiple sexual partners, particularly among HIV-infected MSM.2,6,7

Pelvic Inflammatory Disease: Untreated STDs can cause PID, a serious condition in women. One in eight women with a history of PID experience difficulty getting pregnant. There are no tests for PID. A diagnosis is usually based on a combination of the medical history, physical exams, and other test results. PID symptoms may be mild or nonexistent, resulting in carriers being unaware that they have the disease. However, the following symptoms may occur: pain in the lower abdomen, fever, unusual discharge with bad vaginal odor, pain and/or bleeding during sex, burning sensation during urination, and bleeding between periods.1,2

Screening Methods

Testing for STIs generally involves a blood test and/or self-collection of relevant body fluid specimens.2,8 Testing for HIV is ideally performed with a combination antigen/antibody immunoassay, which requires a blood draw. At the point-of-care, other options for testing can be performed on oral secretions or finger-stick samples.2,9

The following STIs are diagnosed based on tests on blood samples: syphilis—either a nontreponemal or treponemal test; HBV—HBV surface antigen, surface antibody, and core antibody (HBcAb); and HCV—HCV antibody.

The following STIs are diagnosed through testing on nonblood samples: N gonorrhoeae and C trachomatis—nucleic acid amplification testing (NAAT) on urine for men, vaginal swabs for women, urethral swabs, endocervical swabs, and rectal and oropharyngeal swabs; and T vaginalis—NAAT on vaginal swabs or urine.

The advent of urine-based tests and the utility of self-collected vaginal swabs have increased the acceptance of STI screening among patients and providers because it allows for routine specimen collection without a pelvic examination or swab of the urethra.

STD Treatment

For individuals diagnosed with chlamydia, most clinicians will prescribe oral antibiotics. Normally, a single dose of azithromycin (500 mg) or doxycycline (200 mg) twice daily for 7 days is the most common treatment and is the same for those with or without HIV. With treatment, the infection should clear up in about a week.1,2,10

Gonorrhea and chlamydia can occur in tandem, and in these cases a doctor may prescribe a regimen of ceftriaxone (250 mg) plus doxycycline (100 mg) or azithromycin (500 mg). Ceftriaxone is given as a one-time injection. The other antibiotics are taken orally.

Penicillin (2.4 MU) as a single dose continues to be the drug of choice for treatment of primary, secondary, and early latent syphilis. Dosing for late latent or tertiary syphilis is 2.4 MU once weekly for 3 doses.

Trichomonasis: Metronidazole 500 mg twice daily for 5 to 7 days; a single dose of 2 gm is as effective as the prolonged therapy.

HPV: Topical preparations (creams and solutions that the patient applies directly to the affected area), imiquimod, podophyllin, podofilox, fluorouracil (5-FU), trichloroacetic acid, and interferon.

M genitalium: Azithromycin 1 gm once, or 500 mg once plus 250 mg for 4 days.

Genital Herpes: Three antiviral medications have been shown to provide clinical benefit in the treatment of genital herpes: acyclovir (400 mg) twice daily, valacyclovir (1 gm) daily, and famciclovir (250 mg) twice daily.

Single-Tablet Regimen for HIV: One of the biggest recent advances in the treatment of HIV is the development of a single-dose medication—one pill that contains a combination of several different HIV drugs.7 A combination tablet is a big step forward from the cumbersome, multipill drug regimens that used to be the only available options for patients with HIV. Here are several selected examples: bictegravir (50 mg), emtricitabine (200 mg), and tenofovir (25 mg) (Bictarvy); darunavir (800 mg), cobicistat (150 mg), emtricitabine (200 mg), and tenofovir (10 mg) (Symutza); and emtricitabine (200 mg), rilpivirine (25 mg), and tenofovir (25 mg) (Odefsey).

PID: Typically, two antibiotics are prescribed: cefotetan 2 gram, cefoxitin 2 grams IM once plus doxycycline 100 mg twice daily for 14 days, or metronidazole 500 mg twice daily for 14 days.


STDs are a major public health problem that require prompt identification and attention to avoid complications and transmission. This summary article is intended to provide a general overview of STDs.


1. Workowski KA, Bolan GA; CDC. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep. 2015;64(1):1-137.
2. UpToDate. Inc. 2020, Wolters Kluwer Health. Accessed January 2020.
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4. Van Der Pol B, Kwok C, Pierre-Louis B, et al. Trichomonas vaginalis infection and human immunodeficiency virus acquisition in African women. J Infect Dis. 2008;197(4):548-554.
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9. Swartzendruber A, Zenilman JM. A national strategy to improve sexual health. JAMA. 2010;304(9):1005-1006.
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