Lower back pain and vaginal discharge can each develop for a wide range of reasons. These may include infection, pregnancy, or an STI.

Lower back pain and vaginal discharge are common on their own. When they occur together, it can point to an underlying condition.

In this article, learn about seven possible causes of lower back pain and vaginal discharge. We also explore risk factors and treatment options for each issue.

Conditions that cause lower back pain and vaginal discharge include:

1. Urinary tract infection (UTI)

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A UTI may cause lower back pain and increased vaginal discharge.

When a UTI is in the bladder, the condition is called cystitis. When a UTI affects the urethra, the condition is called urethritis. When it is located in the kidneys, this is simply called a kidney infection.

Bacteria are most commonly responsible for UTIs, but fungi and viruses can also cause them.

UTIs can occur in people of any age, including children.

Symptoms of a UTI include:

  • increased vaginal discharge
  • a burning sensation when urinating
  • frequent urges to pee
  • pelvic pain
  • lower back pain
  • weakness and fatigue

2. Pregnancy

Lower back pain and abnormal vaginal discharge can indicate pregnancy. Vaginal discharge may increase in volume and otherwise change during this time.

Increased discharge helps to protect the womb from infection. Even more discharge may appear in the final few weeks of pregnancy.

Lower back pain is also common during pregnancy, especially as the baby grows heavier or moves. These actions can hit nerves that affect the back.

3. Ectopic pregnancy

An ectopic pregnancy occurs when a fertilized egg attaches outside of the uterus, usually to a fallopian tube.

When this happens, a doctor must remove the fertilized egg before it grows too large and causes internal damage.

An ectopic pregnancy can cause:

  • sharp abdominal cramping
  • pain in the rectum
  • severe pain on one side that radiates to the back
  • nausea

4. Reactive arthritis

This condition causes inflammation in the joints. Infection, including those transmitted sexually, can trigger the symptoms.

Reactive arthritis can cause abnormal discharge and lower back pain, but the condition is not linked to serious health risks.

5. Gonorrhea

Gonorrhea is a sexually transmitted infection (STI). Symptoms do not show immediately after transmission, and they may take several weeks to appear.

Because of the delay in symptoms, gonorrhea often goes untreated. This can cause serious health complications, including infertility.

Most women with gonorrhea experience no symptoms. When present, symptoms can include discharge and pelvic pain, which may radiate to the lower back.

6. Pelvic inflammatory disease (PID)

This results from an infection in the upper genital tract. It can appear in the uterus, fallopian tubes, or ovaries.

The disease most commonly develops in women under 25, but it can occur at any age.

PID can cause:

  • vaginal discharge to appear yellow or green
  • pain around the pelvis
  • pain during urination
  • nausea
  • fever

7. Cervical cancer

In rare cases, cervical cancer can cause lower back pain and unusual discharge. Discharge may be pink or smell unpleasant. Pelvic pain is another symptom of this type of cancer.

Cervical cancer often has no symptoms in the initial stages. For this reason, it is important to have regular cervical smear tests, also called Pap smears.

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A urine sample will help a doctor detect infections.

A doctor will begin by asking about symptoms and a person’s medical and sexual history.

The doctor will often request a urine sample, to detect infections such as UTIs. They may also use a swab to take a sample from the inside of the vagina. A lab will test the sample for signs of STIs, including gonorrhea.

Swabs and urine tests can also help to diagnose similar conditions, such as PID.

Pregnancy and ectopic pregnancy can be confirmed with blood or urine tests. If a doctor suspects an ectopic pregnancy, they will perform a physical examination and an ultrasound.

Treatment methods depend on the underlying cause. A doctor may prescribe antibiotics to treat UTIs and some STIs.

They may prescribe antifungal medications, as pills or creams, to treat vaginitis caused by yeast infections.

If a person is experiencing lower back pain and unusual discharge during pregnancy, no treatment may be necessary.

However, if the discharge smells unpleasant or is irritating or painful, this can indicate infection.

Ectopic pregnancies should receive immediate treatment. Doctors usually use a medication called methotrexate, and they may perform surgery to remove the fertilized egg.

Unprotected sexual activity is the most significant risk factor for conditions that can cause lower back pain and abnormal vaginal discharge.

Other risk factors include:

  • poor hygiene
  • not drinking enough water
  • wiping from back to front after using the toilet
  • taking birth control pills
  • having a compromised immune system

However, it is not always possible to prevent the conditions listed above.

For most people, lower back pain and vaginal discharge are not linked to serious health risks. Many common causes can be easily treated with antibiotic or antifungal medications.

Symptoms usually subside within a few weeks, but speak with a doctor if symptoms are severe or persistent.

It is also essential to have regular smear tests to check for HPV and cervical cancer.