Sofie Wise

Mark Spera

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About Author — Mark grew up in a family of healthcare providers and has always been fascinated by preventative medicine, infectious diseases and the intersection of big data and healthcare.

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Chlamydia is the most common sexually transmitted infection (STI) caused by bacteria.

One reason for this is that many people with Chlamydia do not have any symptoms and unknowingly spread the infection.

Left untreated, chlamydia can cause severe complications and even affect your ability to get pregnant.

Therefore, it’s essential for those who come in contact with chlamydia, or suspect they may have chlamydia, to seek treatment in the form of antibiotics as soon as possible.

What is Chlamydia?

Chlamydia trachomatis is a type of gram-negative bacteria that cause infections around the world. It is reliant on living cells to replicate, so much so that it can’t grow in an artificial environment.

The bacteria have a unique life-cycle divided into two principal phases:

  1. Elementary Bodies: Chlamydia takes this form to attach and invade your cells. About eight hours later, the bacteria transform into a second form known as a Reticulate Body.
  2. Reticulate Bodies: In this larger form, Chlamydia can replicate through a process known as binary fission. In binary fission, a bacterium makes a copy of itself and then divides equally into two new bacteria. After about 72 hours, the Reticulate body ruptures, releasing the newly formed Elementary bodies to infect other cells.

What this means is that the rate of re-infection is particularly high in chlamydia. This makes proper chlamydia antibiotic treatment extremely important.


How Is Chlamydia Spread?

Nearly all Chlamydia infections are sexually transmitted in adults and adolescents.

Spread requires intimate sexual contact and Chlamydia cannot be transferred through inanimate objects such as a toilet seat.

Exact transmission rates are difficult to quantify.

One research study found 53% of partners in a sexual relationship with a person with a confirmed infection also had Chlamydia.

Males and females were equally likely to spread the infection to each other. Unfortunately, it is not entirely clear whether having active symptoms increases your risk for transmission.

How Common is Chlamydia?

Chlamydia is the most commonly reported bacterial infection in the United States. According to the Centers for Disease Control and Prevention (CDC), over 1.5 million new Chlamydia infections were reported in 2016.

This high rate of occurrence translates to nearly 500 cases for every 100,000 people, the most cases of any disease ever reported in one year.

The rate of new Chlamydia infections in men increased by an alarming 27% from 2012.

In comparison, the rate of new chlamydia infections in women only increased by 3%. Despite this, the overall rate in women is still nearly twice that of men – however, this is most certainly due to women being more likely to be screened for the infection.

Even still, these rates likely underestimate the actual number of infections greatly since many individuals don’t have obvious symptoms.

Who Is Most Likely to Be Infected by Chlamydia?

Studies have shown chlamydia infections to be the highest among women aged 15 to 24 years. Infection rates are highest in men at a slightly higher age range from 20 to 24 years old.

Population studies have tried to estimate what percent of the overall population is infected by Chlamydia. One extensive study of individuals between the age of 18 and 26 years found 4.2% to have Chlamydia infections.

Another national survey found 1.7% of people between 14 and 39 years had the infection. Out of all states, Alaska had the highest rates of Chlamydia.


What Factors Increase My Risk for Chlamydia Infection?

The following risk factors increase your odds of getting a Chlamydia infection:

  • Being Younger Than 25: Since infection rates are the highest in younger individuals, it makes sense that being under 25 increases your risk. Many experts believe the risk is lower in older adults due to changes in behavior. However, others think your immune system may just be getting stronger against the bacteria due to multiple exposures.
  • New Sexual Partner, or Multiple Partners within 3 Months: These are naturally a risk factor for all sexually transmitted infections. Being more promiscuous increases your chances to have an encounter with someone infected.
  • You’ve had Chlamydia Before: This may denote generally higher risk behavior, or just reinfection with a partner who may or may not know they are infected. (8)
  • You Don’t Always Use a Condom: Barrier type protection, like condom use, can prevent transmission of STIs like Chlamydia.

Chlamydia Signs and Symptoms

Chlamydia Signs and Symptoms in Women

Most woman with Chlamydia will have no symptoms, especially with early infections. However, others can have symptoms that vary with the location of the infection or develop symptoms as the infection progresses.

  • Cervicitis: The cervix is the opening from the uterus, or womb, to the vagina. In women, the cervix is the most common site for Chlamydia infection. Up to 85% of women with a Chlamydial cervical infection will have no signs or symptoms within one year of infection!Some women report vaginal bleeding outside of their period or after sexual intercourse. Others may experience changes in vaginal discharge. It typically takes between one and two weeks for symptoms to develop after you become infected, if you get them at all.
  • Urethritis: About 25% of women with a cervical Chlamydia infection will also have an infection of the urethra, the tube carrying urine from the bladder. While many of these women will not have symptoms, you may experience a set of symptoms similar to a typical urinary tract infection (UTI). Most often this will include pain or burning during urination, a need to urinate more often, or a sudden urge to urinate.
  • Pelvic Inflammatory Disease (PID): Chlamydia can also travel up your reproductive organs, through your uterus and fallopian tubes to your ovaries. Involvement of these structures is known as PID. Spread of Chlamydia in this manner can occur quicker than you may expect. One study found up to 4.5% of women developed PID within 2 weeks of being diagnosed. Unfortunately, the first symptom of PID for many women is difficulty becoming pregnant later in life. Infection of the fallopian tubes connecting the uterus and ovaries can lead to extensive inflammation and scarring. If you do have symptoms early with PID, the most common is pain in the lower abdomen on both sides. This pain can be worsened by intercourse or menstrual period.
  • Other symptoms common to UTI such as abnormal discharge or urinating more often can occur. Abnormal vaginal bleeding also occurs in up to a third of women with PID. Severe cases can cause high fever and loss of bowel sounds.
  • Perihepatitis (Fitzhugh-Curtis Syndrome): Less often, infection with Chlamydia can cause a condition known as Perihepatitis, inflammation of the capsule surrounding your liver. It remains unclear how the infection spreads to the liver but may be due to the response of your immune system or lymphatic system. This condition is most often seen alongside PID, occurring in up to 15% of cases.
  • Infection During Pregnancy: Chlamydia infection during pregnancy brings with it additional risks for both the mother and child. Chlamydia can increase your risk for preterm delivery, with infected mothers delivering before 32 weeks much more frequently than non-infected women. There is also a risk for transmission of the infection to the newborn during birth.

Click here for additional information about symptoms and treatment of chlamydia in women.

Chlamydia Signs and Symptoms in Men

Symptoms of Chlamydia can be vastly different in men, due to the difference in the structures involved in the infection.

  • Urethritis: Chlamydia is the second most common cause of urethritis in men, behind only Gonorrhea. Men are more likely to have symptoms, however, there will still be up to 70% of males who are symptom-free. If they do occur, symptoms will generally begin between five and ten days after infection. When men have symptoms, the most common is a watery or mucous-like discharge from the tip of the penis. Discharge can be minimal and only visible after milking the urethra or staining of your undergarments. If examined under the microscope, two-thirds of discharge will also contain white blood cells. Discharge is frequently accompanied by pain or burning during urination.
  • Epididymitis: This is an infection of the small coiled tube on the back of the testicles through which sperm travels known as the epididymis. Chlamydia is one of the most common causes of epididymitis in men under the age of 35 years old. Many patients will also have urethritis.Chlamydial epididymitis causes one-sided testicular pain, swelling, and tenderness. Ultrasound may show swelling and increased blood flow in the epididymis.
  • Prostatitis: Chlamydia is thought to be a cause of persistent infection of the prostate, a walnut-sized gland situated between the bladder and penis. Men with ongoing prostate infections but no apparent bacterial cause were more likely to have detectable chlamydia in their urine or discharge. Symptoms of prostatitis include pain or burning with urination, difficulty urinating with incomplete emptying of the bladder, pain with ejaculation, or generalized pain in the pelvis.
  • Proctitis: Chlamydial proctitis is an infection of the rectum. This condition primarily results from engagement in anal intercourse. Proctitis symptoms vary depending on the subtype of Chlamydia causing the infection.
  • Reiter Syndrome: About 1% of men with Chlamydia urethritis develop joint pain and swelling known as reactive arthritis. An even smaller number will also develop inflammation in their eye, known as uveitis. Together, these 3 symptoms encompass Reiter Syndrome, a rare condition most commonly attributed to Chlamydia infection.

Chlamydia Symptoms That Can Affect Both Men and Women

  • Conjunctivitis: The subtypes D through K previously mentioned can also affect the conjunctiva, or lining of the eye, to cause pink eye. Pink eye from chlamydia is most often caused by direct contact with secretions from infected genitals. Your white of your eye may appear red, and the lining can look similar to a cobble-stone road.
  • Pharyngitis: While Chlamydia is not a common cause of a sore throat, it has been found residing in the back of the throat. Most researchers believe this isn’t an active infection, but rather a safe place for Chlamydia to hide until it can be spread.

Chlamydia Diagnosis and Screening

How Can You Diagnose Chlamydia Infections?

Testing for Chlamydia infection can be performed in several different ways. The preferred test currently is through nucleic acid amplification testing (NAAT), performed on swabs of vaginal secretions in women or urine in men.

Swabbing the eye lining or opening at the tip of the penis, known as the urethra, can also be performed.

Who Should Be Screened for Chlamydia?

As many infected individuals don’t have symptoms, selective screening should be performed to prevent the abundance of complications that can result from Chlamydia infections.

Females: Both the CDC and US Preventive Services Task Force (USPST) recommend sexually active women 25 years old and younger should be screened for Chlamydia once per year. Sexual orientation does not affect whether you should be tested. If you become pregnant, you should also be screened to prevent the previously mentioned complications. After 25 years old, screening should be performed based on sexual behavior.

Males: The CDC and USPST do not recommend routine screening for men unless they are at an elevated risk of having a Chlamydia infection. If there is suspicion for an infection, men need to be treated to prevent the spread or reinfection of others. High-risk groups who may require more frequent screening include men who have sex with men, HIV+ men, or those with other STIs.

Chlamydia Treatment

What Are the Goals of Treatment for Chlamydia?

Treatment of Chlamydia infections with an antibiotic is recommended to:

  1. Decrease the spread of infection to others, including sexual partners and newborns at the time of delivery. Infections passed to a child during birth can result in severe infections of the eyes or lungs.
  2. Resolve symptoms if you have them. About 85% of patients with symptomatic infections of the urethra or cervix will improve within 2 weeks of starting an antibiotic.
  3. Prevent complications including infertility, chronic pain, and more severe infections.

What Antibiotics Can Treat Chlamydia Infections?


For uncomplicated infections of urethritis or cervicitis, the CDC recommends either 1-gram Azithromycin (Zithromax) given as a single-dose OR 100 mg Doxycycline (Doryx) given twice a day for 7 days.

Cure rates for Chlamydia are similar for both medications, at 96 and 97%, respectively.

Neither medication causes more side effects than the other, with some patients experiencing upset stomach, nausea, or diarrhea. Doxycycline can be cheaper, however, supply can be limited.

Azithromycin does have some advantages. It can get into human cells where Chlamydia hides. It also stays active in the body for up to seven days, so can be given as a one-time oral dose under observation. In contrast, doxycycline requires you to remember to take your medication twice a day for a week, even if you aren’t having symptoms. Azithromycin is also safe to use in pregnancy, which Doxycycline is not.


I’m Allergic to Both These Medications, Are There Other Options?

  • Quinolones: These antibiotics are more expensive than the first-line choices but can still be effective against Chlamydia. Options include either 300 mg Ofloxacin (Floxin) twice a day for 7 days OR 500 mg Levofloxacin (Levaquin) once a day for 7 days.
  • Penicillins or Erythromycin: These medications aren’t as effective as the choices mentioned above, with cure rates less than 90%. (26) However, they can be used in Pregnancy if the mother cannot tolerate Azithromycin.

What If I have a More Severe Chlamydia Infection?

More severe infections typically will require more prolonged or aggressive treatment. It is common also to treat Gonorrhea in these cases, as there are high rates of coinfection. Some examples of treatment regimens are as follows:

  • Proctitis can be treated with 100 mg Doxycycline twice a day plus an injection of 250 mg Ceftriaxone. Severe infections such as LGV may warrant up to 3 weeks of treatment.
  • Epididymitis can be treated with 100 mg Doxycycline twice a day for 10 days plus a single injection of 250 mg Ceftriaxone.
  • Pelvic Inflammatory Disease may need to be treated in the hospital with 100 mg Doxycycline twice a day plus 2-grams IV Cefoxitin every 6 hours for 2 weeks.

Does My Partner Need Therapy?

Yes! Your current partner and any additional sexual partners in the last 60 days should present for evaluation by a physician as well as STI testing. Your partner may not have symptoms, but if they are infected can pass the infection back to you if they are not treated.

Reinfection rates have been observed as high as 30% due to patients resuming sexual activity with their previous partner after treatment.


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