Irregular Periods

A regular period (menstruation) is an important part of reproductive health. Irregular periods occur when an individual's menstrual cycle is shorter or longer than the average length. About 14% to 25% of people experience irregular menstrual cycles.

A normal menstrual cycle lasts 24 to 38 days. It is considered irregular when it is shorter than 24 days or longer than 38 days. Your menstrual cycle may also be irregular if it varies by more than 20 days in length from month to month. 

This article discusses common causes of irregular periods and how to treat them.

A person uses a period tracking app on their phone.
Granger Wootz/Blend Images/Getty Images

Adolescents who have recently begun menstruating may have irregular periods for the first few years. Individuals going through perimenopause also commonly experience irregular periods.

Symptoms of Irregular Periods

Symptoms of irregular periods include:

  • Menstrual cycle shorter than 24 days
  • Menstrual cycle longer than 38 days
  • A menstrual cycle that changes by more than 20 days each month
  • Heavy bleeding
  • Light bleeding
  • Painful periods 

Types of Irregular Periods

Common types of irregular periods include:

Causes of Irregular Periods

Several possible causes of irregular periods include pregnancy, stress, uncontrolled diabetes, uterine cancer, and more. The most common causes of irregular periods are:

  • Pregnancy: During pregnancy, the body stops ovulating, and periods temporarily stop. 
  • Stress: Stress is strongly associated with abnormal menstrual cycles. A review found that high levels of perceived stress are linked with a greater chance of an irregular period.
  • Smoking: Studies show high cigarette use is significantly associated with premature menopause, which means smoking can cause your period to permanently stop earlier than average.
  • Weight changes: Significant weight changes can throw off your period. When the body does not get enough calories, it cannot produce enough hormones to sustain the menstrual cycle. 
  • Obesity: Excess body fat makes extra estrogen. This extra estrogen changes the menstrual cycle and can cause lighter or heavier periods.
  • Intense exercise: Strenuous exercise and resistance training has been found to cause irregular periods in female athletes because it causes a decrease in luteinizing and gonadotropin-releasing hormones. 
  • Birth control pills: Hormonal birth control pills can lead to irregularities. Progestin-only medications may lead to bleeding in between periods. Individuals who stop their birth control pills may experience irregular periods for months. 
  • Uterine polyps and uterine fibroids: Uterine polyps and fibroids are growths that attach to the wall and lining of the uterus. This leads to heavy period bleeding and pain.
  • Endometriosis: This condition causes endometrial tissue to grow outside of the uterus. It can cause abnormal bleeding and significant pain with periods. 
  • Pelvic inflammatory disease (PID): An infection (typically a sexually transmitted infection) in the reproductive organs that leads to inflammation and irregular periods.
  • Polycystic ovary syndrome (PCOS): About 10% of people with irregular periods have PCOS. In this condition, ovarian cysts form, leading to a hormonal imbalance and irregular periods.
  • Premature ovarian insufficiency (POI): When the ovaries stop working before age 40, it causes periods to stop (amenorrhea). It is possible for people with POI to experience occasional periods and even become pregnant.
  • Uncontrolled diabetes: High blood sugar levels alter the hormone levels in the blood and change the menstrual cycle. Fortunately, treating type 1 or 2 diabetes can help periods become more regular.

Less common causes of irregular periods include:

What Medications Can Cause Irregular Periods?

Some medications can cause irregular periods. Long-term use of steroids may cause heavy or irregular periods. Anticoagulant drugs (blood-thinning medications) may cause heavy period bleeding.

How to Treat Irregular Periods

Treatment of irregular periods depends on the underlying cause. Treatment options may include:

  • Hormonal birth control: Birth control pills can treat heavy period bleeding caused by endometriosis, fibroids, and PCOS. 
  • Intrauterine device (IUD): An IUD can be used to lower the amount of period bleeding each month.
  • Gonadotropin-releasing hormone (GnRH) agonists: GnRH agonists may reduce uterine fibroids' size and help regulate the menstrual cycle. 
  • Pain management: Nonsteroidal anti-inflammatory drugs (NSAIDs) like Advil (ibuprofen) or Aleve (naproxen) may be used to treat painful periods. Talk with your healthcare provider before starting a regular NSAID regimen.

Are There Tests to Diagnose the Cause of Irregular Periods?

To determine what might be causing your irregular periods, your healthcare provider may recommend one or more of these tests:

  • Pelvic exam: Your healthcare provider will likely start with a routine pelvic exam to assess your reproductive organs.
  • Blood tests: Heavy periods may cause anemia, so your healthcare provider will check the iron level in your blood. They may also recommend a pregnancy test and hormone levels.
  • Vaginal cultures: Cultures may be taken to test for infection.
  • Pelvic ultrasound: An ultrasound can diagnose uterine fibroids, polyps, or ovarian cysts.

When to See a Healthcare Provider

Regular menstruation is an important factor in reproductive health and fertility. For this reason, you should speak with your healthcare provider any time you experience a significant change in your period. 

See your healthcare provider if you could be pregnant or if you develop any of the following symptoms:

  • High fever
  • Severe pelvic pain
  • Foul-smelling vaginal discharge
  • Unusually heavy bleeding
  • Bleeding between periods 
  • Periods that last longer than seven days


The following lifestyle factors can help keep your periods regular:

  • Healthy diet
  • Moderate exercise schedule
  • Stress-management practices 
  • Adequate rest 
  • Regular visits with your healthcare provider


Your period may be considered irregular if your menstrual cycle is shorter than 24 days or longer than 38 days. Other irregular periods include heavy or light bleeding, bleeding between periods, and painful periods. Irregular periods may be caused by several factors, including pregnancy, stress, smoking, weight changes, and intense exercise. Health conditions that cause irregular periods include uterine polyps and fibroids, endometriosis, PCOS, and more. Treatment may include hormonal birth control, IUD, and pain management techniques. 

A Word From Verywell

Having an irregular period can affect your well-being and quality of life. You should talk with your healthcare provider whenever you experience a significant change in your menstrual cycle. Many causes of irregular periods can be treated or even prevented. In addition to talking with your healthcare provider, consider making any needed lifestyle changes, such as quitting smoking or starting a moderate exercise program. 

Frequently Asked Questions

  • What causes irregular periods?

    Several possible causes of irregular periods include stress, smoking, weight changes, and chronic health conditions. 

  • Can stress cause irregular periods?

    Yes, a high level of stress is strongly linked with irregular periods. A high level of cortisol (known as the stress hormone) can alter the menstrual cycle and lead to irregular periods.

  • How can I treat my irregular periods?

    The treatment for irregular periods depends on the underlying cause. Possible treatment options include hormonal birth control, intrauterine device, and pain management.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Bae J, Park S, Kwon JW. Factors associated with menstrual cycle irregularity and menopause. BMC Womens Health. 2018;18(1):36. doi:10.1186/s12905-018-0528-x

  2. National Institute of Child Health and Human Development. What are menstrual irregularities?

  3. Office on Women’s Health. Period problems.

  4. Miyamoto M, Hanatani Y, Shibuya K. Relationship among nutritional intake, anxiety, and menstrual irregularity in elite rowers. Nutrients. 2021;13(10):3436. doi:10.3390/nu13103436

  5. American College of Obstetricians and Gynecologists. Heavy menstrual bleeding.

  6. Harvard Health. When you visit your doctor: Irregular menstrual periods.

By Carrie Madormo, RN, MPH
Carrie Madormo, RN, MPH, is a health writer with over a decade of experience working as a registered nurse. She has practiced in a variety of settings including pediatrics, oncology, chronic pain, and public health.