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Learn more about breast cysts, including what they are, what causes them and how they can be treated.

1. What are breast cysts?

  1. Breast cysts are a very common benign (not cancer) breast condition
  2. They are 1 of the most common causes of a lump in the breast
  3. They can occur at any age but most often affect women over 35
  4. Most breast cysts do not need to be treated
  5. Having a breast cyst does not increase your risk of breast cancer

2. Symptoms of breast cysts

A breast cyst can feel like a soft or hard lump in the breast.

Cysts are typically oval or round and can develop quickly anywhere in the breast.

They can be any size, ranging from a few millimetres to several centimetres.

Some cysts are too small to feel, while others are large enough to feel uncomfortable. Some cysts may be painful.

It’s common to have more than 1 cyst, and clusters of cysts can form in 1 or both breasts.

Before a period, cysts may become larger and feel sore or tender as hormone levels change. They may then settle when the period has finished.

Many people who have cysts don’t feel them at all.

3. Who breast cysts affect

Women over 35

Breast cysts are most common in women over 35.

You’re more likely to get breast cysts if you are:

  • Between 35 and 50 years old
  • Premenopausal (still have periods)
  • Postmenopausal (no longer have periods) but taking hormone replacement therapy (HRT)

Women of any age

While breast cysts are most common in women over 35, they can happen at any age.

Small cysts (microcysts) are common in young women who have not been through the menopause.

Breast cysts are not common after the menopause.


Breast cysts are very rare in men.

Breast cysts in men are diagnosed and treated in the same way as in women.

4. Causes of breast cysts

Breasts are made up of milk-producing glands (lobules) and tubes that carry milk to the nipple (ducts). These are surrounded by tissue that gives the breasts their size and shape.

Sometimes, the milk glands can fill up with fluid, causing breast cysts.

It’s thought cysts develop naturally as the breast alters with age, due to normal changes in hormone levels.

After the menopause, as levels of the hormone oestrogen fall, cysts usually stop forming. If you use HRT, you may still develop cysts.

Side-on illustration of the breast, with arrows to the chest, lobules, nipple, ducts, fatty tissue and ribs
A breast cyst occurs when a lobule fills with fluid.
A breast cyst occurs when a lobule fills with fluid.

5. Diagnosis

If you see your GP because you have found a breast lump, they may be able to say whether it feels like a cyst. However, they’re still likely to refer you to a breast clinic.

At the breast clinic you’ll have a breast examination. You may also have:

  • A
  • An

An ultrasound scan can help show if a lump is solid or fluid-filled.

If you’re under 40, you’re more likely to have an ultrasound than a mammogram. This is because younger women’s breast tissue can be dense, which can make the x-ray image less clear. Dense means there’s a high amount of breast tissue compared to fat. It can make it harder to identify normal changes or benign conditions like cysts.

However, some women under 40 may still need a mammogram to complete the assessment.

If the lump can be easily felt, your specialist may put a fine needle into it and draw off the fluid to confirm that it’s a fluid-filled cyst.

Breast cysts are sometimes found by chance during a routine screening mammogram or while having investigations at a breast clinic for another reason.

6. Treatment and follow-up

Most breast cysts do not need treatment

If you have a breast cyst, you will not usually need any treatment or follow-up. Most cysts go away by themselves and are nothing to worry about.

How long a cyst lasts varies from person to person. Cysts usually go away after the menopause, but some people have them throughout their life.

Drawing off the fluid (aspiration)

If a cyst is large or causing discomfort, your specialist may draw off (aspirate) the fluid using a fine needle and syringe. Sometimes this is done using ultrasound to help find the cyst.

The fluid drawn off from the cyst can vary in colour and range from clear to very dark.

If the fluid is blood-stained, it will usually be sent to a laboratory to check the reason for this. It may also be sent for testing if there’s evidence of an infection. Blood in the fluid is sometimes caused by the needle used to aspirate the fluid.

Once the fluid has been drawn off, the cyst usually disappears. You might feel some discomfort as the fluid is being drawn off, and the area may feel bruised and tender for a few days afterwards. Taking pain relief like paracetamol can help.

Can breast cysts come back?

Breast cysts can come back or you may develop new cysts. The treatment for cysts is usually the same each time.

It’s important to see your GP if you think your cyst has returned or you have developed a new one.

7. Can breast cysts be prevented?

Cysts happen in response to normal hormone changes and there’s no known way to prevent them.

If you take HRT, this can increase your risk of developing new cysts.

8. Does having breast cysts increase my risk of breast cancer?

Having a breast cyst does not increase your risk of developing breast cancer.

However, it’s important to be breast aware and go back to your GP if you notice any changes in your breasts, no matter how soon after your cyst was found.

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Quality Assurance

This information was published in January 2024. We will revise it in January 2027.

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