Two periods in one month

An adult woman’s menstrual cycle can range in length from 24 to 38 days and in teenage girls it can last even longer. Based on how long your cycle normally lasts, if you think you’re having a second period in that stretch of time, it is important to determine if it is just spotting or menstrual bleeding.

In most cases, having two periods in a month occasionally is not serious. However, if you’re frequently having two periods in one month, you may have an underlying health condition.

What causes menstruation twice a month?

Two periods in one month can be caused by having a shorter menstrual cycle or by an underlying health condition that causes vaginal bleeding.

Reasons your menstrual cycle may suddenly become shorter include stress, illness, extreme weight loss or gain, reacting to hormonal birth control and a failure in the egg releasing from your ovary (anovulation).

In young girls, puberty can cause shorter menstrual cycles, while in older women, this can occur due to menopause.

Health conditions that cause more frequent periods

Health conditions that can cause sudden, shorter menstrual cycles include:

• Fibroids
• Hyperthyroidism or hypothyroidism
• Miscarriage — if you are pregnant, a miscarriage can cause heavy bleeding; contact your doctor or midwife urgently if this occurs
• Pregnancy — early pregnancy can cause spotting, however, you should still tell your doctor or midwife
• Sexually transmitted infections (STIs) — STIs can cause vaginal bleeding and discharge
• Uterine cysts

Risk factors for frequent menstruation

You are more at risk of having two periods in one month, if you have a family history of uterine cysts, fibroids or early onset menopause.

When to see a doctor for frequent menstruation

You should see your GP if you are menstruating more often and have: 

• Dark clots in your menstrual blood
• Heavy periods
• Lower abdominal pain that doesn’t get better after a few days
• More menstrual cramps than usual
• Pain during sex
• Spotting or bleeding in between your periods — you may mistake this for two periods in one month

Treatment for frequent menstruation

The treatment for frequent menstruation depends on the underlying cause. If you have just started having periods or you normally have shorter menstrual cycles, you won’t need any treatment. However, if your doctor is concerned that the frequency of blood loss due to your periods is causing anaemia, they may suggest taking iron supplements.

In some cases, hormonal birth control may be recommended to treat frequent menstruation.