Sexually Transmitted Infection (STIs) That Are Curable

While there are some sexually transmitted infections (STIs) that are incurable, there are others that are completely curable: syphilis, gonorrhea, chlamydia, and trichomoniasis. Each is effectively treated with one or more doses of an antibiotic drug, taken either by mouth or given by injection.

Despite effective treatments, it is estimated that 374 million new cases of syphilis, gonorrhea, chlamydia, and trichomoniasis occur worldwide every year. In the United States alone, over 12 million new cases of these four infections were reported in 2021, according to the Centers for Disease Control and Prevention (CDC).

This article will describe the causes and symptoms of four curable sexually transmitted infections, including how each is treated.

Rodolfo Parulan Jr. / Getty Images

A Note on Gender and Sex Terminology

Verywell Health acknowledges that sex and gender are related concepts, but they are not the same.

Sex refers to biology: chromosomal makeup, hormones, and anatomy. People are most often assigned male or female at birth based on their external anatomy; some people do not fit into that sex binary and are intersex.
Gender describes a person's internal sense of self as a woman, man, nonbinary person, or another gender, and the associated social and cultural ideas about the roles, behaviors, expressions, and characteristics.

Research studies sometimes don't use the terminology in this way. Terms that describe gender ("woman," "man") may be used when terms for sex ("female," "male") are more appropriate. To reflect our sources accurately, this article uses terms like "female," "male," "woman," and "man" as the sources use them.

Syphilis

Syphilis is an STI caused by corkscrew-shaped bacteria known as Treponema pallidum. The bacteria are passed from person to person through unprotected oral, anal, and vaginal sex.

Syphilis causes highly contagious, open sores known as chancres, primarily on the penis, anus, and vagina. In addition to being sexually transmitted, syphilis can be passed to a developing fetus during pregnancy.

Syphilis is not spread through casual contact with objects. You cannot get syphilis from a toilet seat, bathtub, hot tub, swimming pool, eating utensils, or sharing linens, towels, or clothes with someone who has it.

In 2021, 176,713 cases of syphilis (all stages and congenital syphilis) were reported in the United States, including 53,767 cases of primary and secondary syphilis—the most infectious stages of the disease.

Symptoms

Syphilis has been called the "Great Imitator" because its symptoms are often confused with other infections. People with syphilis can sometimes go for years without symptoms. In fact, in the early stages, the painless sores may go unnoticed, particularly if they are hidden in the vagina or anus.

Syphilis progresses in four characteristic stages, and symptoms vary by the stage as follows:

Primary stage: Typically, during this stage, a single round, painless chancre erupts on the genitals, vagina, or anus 10 to 90 days after infection. The chancre will last for three to six weeks and heals without treatment.
Secondary stage: Even as the chancre starts to heal, secondary symptoms can develop, such as a rash (including on the palms of the hands and soles of the feet) and flu-like symptoms like fatigue, fever, sore throat, and muscle aches. This stage can last two to six weeks.
Latent stage: The latent stage is the long period in which there are few, if any, symptoms. Latency can last for decades, and, for some people, the infection may not progress beyond this stage.
Tertiary stage: This is the most advanced stage when syphilis can reap sudden, severe damage to the brain, nerves, eyes, heart, blood vessels, liver, bones, and joints. It can occur 10 to 30 years after initial infection and can be deadly without aggressive antibiotic treatment.

Treatment

In its early stages, syphilis is easily treated with a single dose of penicillin given by intramuscular injection (a shot into a large muscle). At later stages, different forms, doses, and durations of penicillin therapy (including intravenous treatment) may be needed to resolve the infection.

Other antibiotics may be used if a person has a penicillin allergy. Even so, the dangers of tertiary syphilis are so great that penicillin should still be used, albeit with penicillin desensitization therapy to reduce your sensitivity to the drug.

After you complete treatment, follow-up testing is recommended to ensure the infection has cleared. It is also important to make sure any sex partners are also tested and treated for syphilis. Its symptoms are not always obvious, and sores can be hard to see.

Having syphilis once does not protect you from getting it again. If your partner isn't tested and treated, you run the risk of re-infection.

Gonorrhea

Gonorrhea is an STI caused by a bacteria known as Neisseria gonorrhoeae. Infection occurs through unprotected anal, vaginal, or oral sex. Ejaculation of semen is not required for infection to occur. Gonorrhea can also be passed to the fetus during pregnancy.

In 2021, the CDC estimated that 1.6 million people were newly infected with gonorrhea in the United States.

Symptoms

Many males with gonorrhea have no symptoms. If they do, they usually appear within a week of infection and cause:

Burning with urination
A white, green, or yellow discharge from the penis
Painful or swollen testicles

Females frequently have only minor symptoms or no symptoms at all. If they do, they include:

Pain or burning with urination
Vaginal discharge
Vaginal bleeding between periods

Both males and females can get rectal gonorrhea, causing symptoms like:

Rectal discharge
Anal itching or pain
Anal bleeding
Painful bowel movements

A gonorrhea infection in the throat may cause a sore throat or no symptoms at all.

Treatment

There are several antibiotics that are successful in treating gonorrhea. However, gonorrhea strains that are resistant to antibiotics are becoming more and more common.

Today, a single dose of the antibiotic drug ceftriaxone is the preferred treatment for gonorrhea, which is given by intramuscular injection.

If gonorrhea is left untreated, it can cause other serious and possibly permanent complications like:

Chlamydia

Chlamydia is the most frequently reported STI in the world, caused by a bacteria known as Chlamydia trachomatis. Because the symptoms of chlamydia are usually mild or absent, people who have chlamydia are unaware of the infection.

Chlamydia is spread from person to person during unprotected anal, vaginal, or oral sex. In addition, chlamydia can be passed to newborn babies during vaginal childbirth.

Chlamydia frequently co-occurs with gonorrhea, so most tests used to detect chlamydia also detect gonorrhea so that both can be treated together if needed.

In 2021, the CDC estimated that 4 million people were newly infected with chlamydia in the United States. People under 25, those in a non-mutually monogamous relationship, and males who have sex with males have a higher risk of being infected.

Annual testing is recommended for sexually active females who are younger than 25, older people with other risk factors, pregnant women, and males who have sex with males. In some cases, more frequent testing may be recommended.

Symptoms

About 75% of females and 50% of males who have chlamydia have no symptoms. If symptoms appear, they usually do so one to three weeks after infection.

In females, symptoms of chlamydia include:

Vaginal discharge
Burning or pain during urination
Abdominal and/or low back pain
Nausea
Fever
Pain with intercourse
Vaginal bleeding between periods

Symptoms of chlamydia in males include:

Burning or pain during urination
Penile discharge
Burning and itching in the urethra (the tube through which urine exits the body)

If left untreated, chlamydia can cause permanent damage to the reproductive system and lead to infertility. As with gonorrhea, chlamydia can cause PID.

Treatment

The preferred treatment of chlamydia consists of a seven-day, twice-daily course of the antibiotic doxycycline. Alternative treatments include a single dose of the antibiotic azithromycin or a seven-day, once-daily course of the antibiotic levofloxacin.

Trichomoniasis

Trichomoniasis is the most common curable STI in the United States. It affects both males and females, but symptoms are more common in females. The disease is caused by a one-celled parasite known as Trichomonas vaginalis.

Trichomoniasis is spread from person to person by way of unprotected sex, mainly vaginal intercourse.

In 2021, the CDC estimated that 6.9 million people were newly infected with trichomoniasis in the United States.

Symptoms

Many people with trichomoniasis have no symptoms. If symptoms occur, they usually appear within four weeks of exposure to the parasite.

Symptoms of trichomoniasis in females include:

Genital inflammation
Foul-smelling, yellow-green vaginal discharge
Pain with intercourse or urination
Vaginal irritation and itching
Abdominal pain

Symptoms of trichomoniasis in males :

Irritation and itching of the urethra
Penile discharge
Burning after urination
Buring after ejaculation ("cumming")

In pregnant people, having trichomoniasis increases the risk of preterm (premature) birth and low birth weight.

Treatment

Females with trichomoniasis are easily treated with a single dose of an antibiotic called metronidazole, which can treat certain parasitic infections as well as bacterial ones.

In males, the infection will usually go away without treatment. However, because males are often unaware of their infection, they can reinfect their female partner again and again.

Therefore, treatment of both partners is recommended when one partner is diagnosed with trichomoniasis. This can better ensure the cycle of reinfection is stopped.

Prevention

The only way to completely prevent contracting an STI is by abstaining from sexual contact, including oral, vaginal, or anal sex. That said, STIs can largely be prevented with consistent and correct condom use.

Both traditional external condoms and internal condoms (formerly known as female condoms) are equally effective at reducing the risk of STIs. Additionally, regular use of dental dams—latex or polyurethane sheets used between the mouth and vagina or anus during oral sex—can further reduce your exposure.

You can also lower your risk of an STI by practicing monogamy—a long-term, mutually exclusive relationship with one partner. If you have multiple sex partners, it is important to get tested regularly and encourage your partners to be tested as well.  

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