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NHS Choices Condition

Content supplied by NHS Choices

Stretch marks appear when your skin is stretched suddenly. They occur in the strong middle layer of your skin (the dermis), which supports your skin's outer surface (the epidermis).

Rapid growth

The dermis is made up of strong fibres that connect to eachother and allow your skin to stretch as your body grows. However, if a part of your body grows rapidly over a short period of time, the fibres can become thin and over-stretched and some of them may break.

Where the fibres in the dermis break, tiny tears develop and the blood vessels that lie under your skin show through. This is why stretch marks look reddish in colour when they first appear. Eventually, the blood vessels contract to leave only the fat under your skin visible, and the stretch marks fade to a silvery white or grey colour.

Not everyone gets stretch marks. It may be that some people are more likely to develop stretch marks than others because their bodies produce a larger amount of a hormone called cortisol. Cortisol decreases the amount of collagen in your skin, which is a protein in the skin fibres that helps to keep it stretchy.

Several other factors can either cause stretch marks or make developing them more likely. These are outlined below.


If you are pregnant, it is likely that you will develop stretch marks, particularly after the sixth month of your pregnancy.

Hormones that are produced by your body during pregnancy help to soften the ligaments (strong bands of tissue connecting joints) in your pelvis, so that they give more when you come to deliver your baby. However, these hormones also soften the fibres in your skin, making you prone to stretch marks.

As your baby grows, you may develop stretch marks on your abdomen (stomach) as your skin is gradually stretched further and further. Stretch marks may also appear on your thighs and breasts as they get bigger and heavier.

Gaining weight quickly

You may find that you have stretch marks if you put on a lot of weight over a short period of time. The stretch marks may remain even if you lose the weight that you have gained. However, they should fade over time.

If you diet regularly, stretch marks can form as your weight goes up and down rapidly. If you are dieting, it is important to lose weight slowly and steadily so that your skin is not put under strain.

Bodybuilders and athletes may also get stretch marks as their muscles increase in size.


Young people tend to grow very quickly during puberty. During puberty your body develops in growth spurts, bit by bit.

Males often get stretch marks on their shoulders and back, whereas females tend to get them on their hips, thighs and breasts.

Family history

If you have close relatives who have stretch marks (such as your mother) you may be more likely to develop them yourself. Stretch marks may affect both male and female members of your family, although they are more likely to occur in women.

Certain medications

You may find that you develop stretch marks if you use corticosteroid medicines, such as creams, lotions or tablets for eczema (a skin condition that causes itching and redness).

Corticosteroids work in a similar way to the hormone cortisol, which is produced naturally in your body. Medicines that contain corticosteroids can ease the inflammation that is caused by skin conditions, but they can also decrease the amount of collagen that is in your skin.

Collagen is needed to keep your skin stretchy, so the less there is in your skin, the more likely it is that stretch marks will develop.

Certain health conditions

Sometimes, stretch marks can be caused by a rare underlying condition, such as Cushing's syndrome or Marfan syndrome.

Cushing's syndrome

Cushing's syndrome occurs when the body produces an excess amount of cortisol, the same hormone that may make some people more prone to stretch marks than others.

In Cushing's syndrome, your body produces so much cortisol that it can cause a variety of symptoms including:

  • weight gain,
  • back pain, and
  • excessive body and facial hair.

If you have Cushing's syndrome your stretch marks may be quite noticeable and dark in colour.

Marfan syndrome

Marfan syndrome is caused by a faulty gene that affects your body's connective tissues, including your skin. It weakens your body's tissues and affects their elasticity (ability to stretch), so that your skin is not as resistant to stretch marks as it should be.

If you have Marfan syndrome you may have stretch marks on your shoulders, hips or lower back, although the condition also causes several other symptoms, such as curvature of the spine and problems with vision.

view information about Stretch Marks on www.nhs.co.uk »

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