Endometriosis occurs when tissue similar to the uterine lining, or endometrium, grows outside of the uterus. Endometriosis can cause symptoms like:

  • painful, heavy periods
  • fatigue
  • weight gain
  • mood changes

Hormones, especially estrogen and progesterone levels, play a major role in endometriosis. The growth and symptoms of endometriosis are connected to changes in these hormone levels.

Endometriosis treatment typically involves regulating estrogen and progesterone levels. Treatment can help prevent further growth of endometriosis and manage its symptoms.

Here’s what to know about endometriosis and your hormones.

Estrogen is a hormone associated with feminine characteristics. It’s important to note that not everyone with high levels of estrogen identifies as female.

Estrogen is involved in many different body systems. It plays a role in the development and functions of the:

  • uterus
  • breasts
  • vagina
  • ovaries

It plays a major role in reproduction and regulating the menstrual cycle.

It’s also involved in maintaining:

  • bones
  • hair
  • blood vessels
  • pelvic muscles

Estrogen is mainly developed in the ovaries. Fat cells and adrenal glands also produce small amounts.

Some research suggests that endometrium growing outside the uterus produces extra estrogen. This leads to overall higher levels of estrogen in the body.

Endometriosis is considered an estrogen-dependent condition. The elevated estrogen levels that occur with endometriosis trigger inflammation and the growth of endometrium in the body. It contributes to endometriosis symptoms like:

  • heavy, painful periods
  • weight gain
  • fatigue
  • mood changes

Progesterone is a natural sex hormone the female body secretes after ovulation. This hormone is essential for regulating your menstrual cycle and maintaining a healthy pregnancy. Progesterone also plays a role in preventing excess growth of endometrium.

Low levels of progesterone plus increased estrogen levels are thought to simultaneously play a role in endometriosis.

Synthetic progesterone, known as progestin, may be used to treat endometriosis. However, even if your body is making adequate levels of progesterone or you’re taking progestin, endometriosis can still occur or become bothersome.

With endometriosis, endometrium can become resistant to the protective benefits of progesterone or progestin.

People who have endometriosis typically have imbalanced levels of estrogen and progesterone in the body. This can impact endometriosis in many ways.

Hormones and heavy, painful periods

Your menstrual cycle is driven by fluctuations in hormone levels, especially estrogen and progesterone.

Estrogen and progesterone work together to prepare for a possible pregnancy each month. If pregnancy does not occur, these hormone levels start to drop after ovulation. This triggers the uterine lining to start breaking down and shedding with your period.

With endometriosis, the endometrium tissue grows outside of the uterus, throughout the pelvic area. It can attach to the outside of the uterus, ovaries, fallopian tubes, and bowels.

This tissue responds to the same hormonal changes as your uterine lining. It swells and bleeds every month like your uterine lining.

Though this tissue has nowhere to go. It can get trapped in your body and lead to inflammation and bleeding. This can contribute to heavy periods or bleeding between periods.

When this excess tissue growth gets trapped and becomes inflamed, it also leads to pain.

Hormones and weight gain

Some people living with endometriosis feel the condition leads to weight gain. This is often thought of as water weight.

Estrogen is known to trigger fluid retention, while progesterone acts as a diuretic to help remove excess fluid from the body.

Endometriosis can lead to bloating and make it seem like your clothes don’t fit as well as they used to. It can feel like weight gain.

This perceived weight gain can happen because of imbalanced levels of estrogen and progesterone in your body.

Weight gain can also occur as a side effect of certain endometriosis treatments.

Hormones and fatigue

An imbalance of hormone levels in your body can also contribute to fatigue, a common endometriosis symptom. A small, qualitative 2020 study found that the vast majority of females living with moderate to severe endometriosis experienced bothersome fatigue.

Though fatigue is often mainly considered a result of the body’s effort to remove the endometrium.

Hormones and mood

Low estrogen levels have been associated with mood swings and can trigger premenstrual syndrome (PMS). In the few weeks after ovulation leading up to your period, estrogen levels drop. People living with endometriosis may feel heightened mood shifts at this time.

Mood changes can also be a result of certain endometriosis treatments.

Gonadotropin-releasing hormone (GnRH) analogues may be used to treat endometriosis. This type of drug blocks the production of estrogen to lower the overall amount of estrogen in your body.

This can be very effective for managing endometriosis. But because estrogen has many other jobs in the body, GnRH meds are typically only used short term.

One of the major side effects of GnRH is an increase in anxiety and depression. This may be due to the dramatic drop in estrogen levels caused by these meds.

Mood changes are also a common side effect of hormonal contraceptives. These work to manage endometriosis by stabilizing estrogen or progesterone levels or both.

An imbalance of progesterone and estrogen contributes to endometriosis. Endometriosis treatment often involves regulating hormone levels to help manage symptoms and slow the growth of endometriosis.

Common endometriosis treatments include:

  • Hormonal contraception. Available in the form of a pill, shot, patch, ring, or intrauterine device (IUD), these medications can lower the amount of estrogen in your body, increase levels of progesterone in the body, or both. This helps reduce the buildup of endometrium and can alleviate endometriosis symptoms.
  • GnRH analogues. These medications block the production of hormones that regulate your menstrual cycle. They help with endometriosis by significantly lowering estrogen in your body. In most cases, they are only recommended for short-term use due to negative effects.
  • Removal of endometrial lesions. The buildup of endometrial tissue outside the uterus can be surgically removed. It can be cut out or burned away. Surgical removal can be an effective way to reduce endometriosis pain.
  • Surgery to remove the uterus and ovaries. In some cases, the uterus can be surgically removed, either with or without the ovaries. Symptom relief can come from no longer having periods. If the ovaries are also removed, it results in a drop in estrogen production, which triggers menopause. This is major surgery and is a big decision not to be taken lightly.

The relationship between endometriosis and hormone levels is complicated. It’s thought to be related to an imbalance of estrogen and progesterone in the body.

Many of the treatments for endometriosis involve ways to rebalance these hormone levels. Reducing estrogen levels can help relieve symptoms and prevent further endometrium growth.