What Causes Menstrual Irregularity?

Medically reviewed by Nicole Galan, RN on February 1, 2016 Written by Ann Pietrangelo

The duration and severity of menstrual bleeding varies from woman to woman. It’s known as menorrhagia if a woman’s menstrual period is excessively heavy, prolonged, or irregular. Symptoms of menorrhagia include a menstrual period that lasts longer... Read More

The duration and severity of menstrual bleeding varies from woman to woman. It’s known as menorrhagia if a woman’s menstrual period is excessively heavy, prolonged, or irregular.

Symptoms of menorrhagia include a menstrual period that lasts longer than seven days, and bleeding is so heavy that you must change your tampon or pad more than once per hour. You should see your doctor if you have excessively heavy or prolonged menstrual periods that interfere with your daily life.

Excessive bleeding can cause anemia, or iron deficiency, and may signal an underlying medical condition. In most cases, a doctor can successfully treat abnormal periods.

What Causes Heavy or Irregular Menstrual Periods?

Heavy or irregular periods can be due to a variety of factors, including:


Some anti-inflammatory drugs, anticoagulants, or hormone medications can affect menstrual bleeding.

Heavy bleeding can be a side effect of intrauterine devices used for birth control.

Hormone Imbalances

The hormones estrogen and progesterone regulate the buildup of the lining of the uterus. An excess of these hormones can cause heavy bleeding. Hormone imbalances are most common among girls who began menstruating in the past year and a half. They’re also common in women who are getting close to menopause.

Medical Conditions


Pelvic inflammatory disease (PID) and other infections can cause irregular periods, as can endometriosis. This is a condition in which tissue that lines the inside of the uterus begins to grow elsewhere inside the body. This can cause heavy bleeding, as well as pain.

Inherited Blood Disorder

Heavy menstrual bleeding can also be due to some inherited blood disorders that affect clotting.

Benign Growths or Cancers

Cervical, ovarian, or uterine cancer can all cause heavy bleeding, but these conditions are not common. Benign, or noncancerous, tumors in the uterus can cause heavy bleeding or long periods. Benign growths in the uterine lining (endometrium) can cause a heavy or prolonged period. These growths are known as polyps, when the growth is made up of endometrial tissue, or fibroids, when the growth is made up of muscle tissue.

Other Possible Causes


Lack of ovulation, or anovulation, results in a lack of the hormone progesterone, causing heavy periods.


When glands from the uterine lining embed in uterine muscle, heavy bleeding can occur. This is known as adenomyosis.

Ectopic Pregnancy

You should contact your doctor if you bleed during pregnancy. Normal pregnancy interrupts menstruation. Some spotting during pregnancy, especially during the first trimester, is often nothing to worry about. Seek immediate medical attention if you bleed heavily during pregnancy. It can be a sign that the fertilized egg implanted in the fallopian tube rather than the uterus, which is called an ectopic pregnancy. It can also indicate a miscarriage. Your doctor will be able to help you figure out what’s causing any bleeding during pregnancy.

What Are the Symptoms of Heavy or Irregular Periods?

The length of the menstrual cycle and amount of blood flow is unique to each woman. However, most women have a cycle that ranges from 24 to 34 days. Blood flow averages about four or five days, with a blood loss of about 40 cc (3 tablespoons). It’s important to remember that these are just averages, and that your “normal” may fall outside of these ranges.

A blood loss of 80 cc (5 tablespoons) or more is an abnormally heavy flow. Signs that your flow may be abnormally heavy include soaking through more than one tampon or sanitary pad in an hour, for several hours at a time. You may need to double up on sanitary pads, or use both a tampon and a pad. An abnormally heavy flow may cause you to wake up during the night because you need to change protection. You may not be able or willing to participate in your normal activities because your flow is too heavy. Sometimes, an abnormally heavy flow will contain large blood clots, or last more than a week. Also, an abnormally heavy flow can cause you to experience the following symptoms, which may be an indication of anemia:

  • fatigue
  • pale skin
  • shortness of breath
  • dizziness

While every woman’s cycle is different, irregularities such as bleeding mid-cycle or bleeding after intercourse are abnormal symptoms.

When Should I Seek Medical Care?

You should see your gynecologist once a year for a checkup. However, you should make an appointment right away if you have bleeding or spotting in the following circumstances:

  • between periods
  • after sex
  • while pregnant
  • after menopause

Other indicators that you should consult your doctor include the following:

  • if your periods consistently last for more than a week
  • if you require more than one tampon or sanitary pad in an hour, for several hours in a row
  • severe pain
  • fever
  • abnormal discharge or odor
  • unexplained weight gain or loss
  • unusual hair growth
  • new acne
  • nipple discharge

Keep track of your menstrual cycles, including how long your blood flow lasts, and how many tampons or sanitary pads you use during each cycle. This information will be helpful at your gynecological appointment.

Avoid products that contain aspirin because they may increase bleeding.

How Are Heavy or Irregular Menstrual Periods Diagnosed?

If you have abnormal menstrual periods, your doctor will probably begin with a pelvic examination. They will take your medical history, and you should list all the medications and supplements you’re taking.

Depending on your specific symptoms, diagnostic testing may include:

Pap Smear

This test is to check for various infections or cancerous cells

Blood Tests

Blood tests will be used to check for anemia, blood-clotting problems, and thyroid function.

Pelvic Ultrasound

A pelvic ultrasound will produce images of your uterus, ovaries, and pelvis.

Endometrial Biopsy

If your doctor wants to evaluate possible issues with your uterus, they may order an endometrial biopsy, in which a sample of your uterine tissue is taken so it can be analyzed. They may also use a diagnostic hysteroscopy to view the inside of your uterus. For a hysteroscopy, your doctor will use a lighted tube to view the uterus and remove the polyp.


They may also use a sonohysterogram, an ultrasound that involves the injection of fluid into your uterus to help make an image of your uterine cavity. Your doctor will then be able to look for polyps or fibroids.

Pregnancy Test

Your doctor may request a pregnancy test.

What Are the Treatment Options for Heavy or Irregular Menstrual Periods?

Treatment will depend on your overall health, the reason for your menstrual abnormalities, and your reproductive history and future plans. Your doctor will also need to address any underlying medical conditions, such as thyroid dysfunction. Treatments may include the following.


Possible medication treatments your doctor may suggest include:

You can work with your doctor to find alternatives if your irregularities are due to medications you are already taking.

Medical Procedures


Dilation and curettage, also known as D&C, is a procedure in which the doctor dilates your cervix and scrapes tissue from the lining of your uterus. This is a fairly common procedure and generally cuts down on menstrual bleeding.


Surgery is the common treatment for cancerous tumors. Surgery is also an option to treat fibroids, but it’s not always necessary. Removal of polyps can occur using a hysteroscopy.

Endometrial Ablation

Endometrial ablation is a procedure used in women who have had no success with medications to control heavy bleeding and related symptoms. In this procedure, the doctor will destroy the uterine lining, leaving little or no menstrual flow. Endometrial resection removes the uterine lining. This procedure significantly decreases your chances of a future pregnancy, so women who plan on having children should discuss and consider other treatment options.


Hysterectomy is the surgical removal of the uterus and cervix. This may be the preferred treatment for those with cancers or fibroids. It can also treat endometriosis that hasn’t responded to other less invasive forms of treatment. A hysterectomy will end your ability to bear children. Your doctor will also remove your ovaries, if necessary. This results in premature menopause.

What Are the Complications Associated with Heavy or Irregular Menstrual Periods?

Heavy blood flow isn’t always a sign that something is wrong. However, excessive loss of blood can deplete the body’s supply of iron and cause anemia. A mild case of anemia can cause fatigue and weakness. A more severe case can result in the following symptoms:

  • headaches
  • dizziness
  • shortness of breath
  • rapid heart rate

A very heavy flow can also cause painful cramping, or dysmenorrhea, which sometimes requires medication.

Medically reviewed by Nicole Galan, RN on February 1, 2016 Written by Ann Pietrangelo

18 possible conditions

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This feature is for informational purposes only and should not be used to diagnose. Please consult a healthcare professional if you have health concerns.

Medically reviewed by Nicole Galan, RN on February 1, 2016 Written by Ann Pietrangelo