Stretch Marks: Why They Form and What Helps

What stretch marks are

Stretch marks are a form of scarring. When skin stretches faster than it can adapt, the collagen and elastic fibers in the dermis break. The overlying skin thins and the damaged area heals with flattened, less elastic tissue.

They go through two stages:

On darker skin, new stretch marks can look dark brown or purple and fade to lighter lines.

The most common places are the belly, breasts, hips, thighs, buttocks, upper arms, lower back and, in growing teens, around the knees.

What causes stretch marks

Pregnancy

Up to 90% of pregnant people develop stretch marks (striae gravidarum), usually in the third trimester on the belly, breasts and thighs. Risk is higher with younger age, a family history, higher weight gain, a large baby or twins, and more amniotic fluid.

Puberty

Rapid growth causes stretch marks on the thighs, buttocks, hips and breasts in girls, and the back, shoulders and thighs in boys. They are a normal part of adolescence. See adolescent growth spurts.

Weight gain and muscle building

Rapid weight gain or obesity, and rapid muscle growth from weight training, especially with anabolic steroids, can cause stretch marks on the shoulders, chest, arms and thighs.

Steroids

Corticosteroids weaken collagen. Stretch marks can follow:

• strong steroid creams used for long periods, especially in skin folds such as the groin and armpits
• long-term steroid tablets
• inhaled steroids at high doses, rarely

Cushing syndrome

Cushing syndrome is a condition of too much cortisol, from steroid medicines or, less often, a pituitary or adrenal tumor. Its stretch marks are typically wider than 1 cm and deep purple, on the belly, flanks, thighs and breasts. Other signs include weight gain around the trunk, a round face, a fatty hump between the shoulders, thin skin that bruises easily, weak thigh muscles, high blood pressure and high blood sugar.

Genetic connective tissue conditions

• Marfan syndrome: stretch marks without weight change, tall stature, long fingers and lens dislocation.
• Ehlers-Danlos syndrome: stretchy, fragile skin and very flexible joints.

Other causes

Rapid breast enlargement after implants, and some medical conditions such as anorexia nervosa recovery, can also cause striae.

Do stretch marks need tests?

Ordinary stretch marks need no tests. A doctor will consider further investigation only if there are signs of Cushing syndrome (urine or saliva cortisol tests and an overnight dexamethasone suppression test) or a genetic condition (examination, heart scan and genetic testing).

Stretch marks treatment

Treatment can make stretch marks less noticeable but cannot remove them completely. Early red marks respond much better than old white ones. Many treatments are not suitable during pregnancy.

Topical treatments

• Tretinoin cream (prescription): can improve the appearance of early stretch marks when used for several months. Retinoids must not be used in pregnancy, and use while breastfeeding should be discussed with a doctor.
• Hyaluronic acid: may help early stretch marks when applied regularly.
• Centella asiatica creams have some evidence for prevention in pregnancy.
• Cocoa butter, olive oil and vitamin E: popular but studies show no clear benefit over moisturizer alone. Massaging any moisturizer in daily may help a little and relieves itching.

Procedures

• Pulsed dye laser: reduces redness in early marks.
• Fractional lasers (non-ablative and ablative): stimulate new collagen and improve texture of both early and older marks.
• Microneedling and radiofrequency microneedling: improve texture and color, especially combined with other treatments.
• Microdermabrasion and chemical peels: modest improvement.
• Excimer laser or light: can help repigment white marks temporarily.

These procedures need several sessions, are not covered by insurance as cosmetic treatments, and carry a risk of pigment changes, particularly in darker skin. Choose a board-certified dermatologist.

Surgery

A tummy tuck (abdominoplasty) removes stretch-marked skin below the belly button, but it is a major operation and only appropriate for other reasons too, such as excess skin after weight loss or pregnancy.

Can you prevent stretch marks?

There is no proven way to prevent them entirely, because genetics play a big part. These steps may help:

• gain weight gradually during pregnancy, following your clinician's guidance
• keep skin moisturized, which also reduces itching
• avoid rapid weight swings
• use steroid creams only as directed and for the shortest time needed

Frequently asked questions

What causes stretch marks?

Stretch marks form when skin stretches quickly and the collagen and elastic fibers in the dermis tear. Common triggers are pregnancy, puberty growth spurts, rapid weight gain and muscle building. Steroid medicines, Cushing syndrome and some genetic conditions also cause them. Genetics affect how likely you are to get them.

Do stretch marks go away?

They do not disappear completely, but they fade a lot over time. Red or purple marks usually turn pale and silvery over 6 to 12 months or more, becoming much less noticeable. Treatment works best while marks are still red.

What is the best treatment for stretch marks?

For early red marks, prescription tretinoin, pulsed dye laser and fractional laser treatments have the best evidence. Older white marks respond best to fractional lasers and microneedling. Expect improvement, not complete removal. Retinoids are not safe in pregnancy.

When are stretch marks a sign of something serious?

Stretch marks are a concern when they are wide (over 1 cm) and dark purple, appear without weight gain or growth, or come with a round face, weight gain around the middle, easy bruising, muscle weakness or high blood pressure. These can be signs of Cushing syndrome.

Do creams prevent stretch marks in pregnancy?

The evidence is weak. Cocoa butter and olive oil have not been shown to prevent stretch marks in good studies. Some creams containing centella asiatica or hyaluronic acid show modest benefit. Moisturizing does reduce itching and dryness, so it is still worthwhile.