Stretch Marks (Striae): Why They Appear, Red versus White Stretch Marks, and Which Treatments Have Evidence?

What is a stretch mark (stria)?

A stretch mark is a type of scar that forms when the collagen and elastin fibres in the middle layer of the skin (the dermis), which give the skin its strength and elasticity, tear. When the skin stretches or shrinks rapidly, these fibres are damaged; line-shaped scars appear during healing. They are seen most often on the abdomen, breasts, hips, thighs, lower back, back and upper arms.

Stretch marks are medically harmless and not contagious. They are very common: stretch marks that appear in pregnancy are reported to occur in more than half of women. Seeking treatment is entirely a personal choice; a stretch mark is not a sign of a lack of care or of neglect.

Why do stretch marks appear?

Hormones and inherited predisposition play as much of a part in the formation of stretch marks as the mechanical stretching of the skin. This is why, of two people who gain the same weight, one develops stretch marks and the other does not. The main causes are:

• Pregnancy: seen on the abdomen, breasts and thighs, especially in the final months.
• Rapid growth in height during puberty: horizontal lines on the back in boys and stretch marks on the hips and thighs in girls are common and often fade on their own.
• Rapid weight gain or rapid weight loss
• An increase in muscle mass over a short period (intensive weight training)
• Long-term corticosteroid use: applying strong corticosteroid creams to the same area for a long time, or taking corticosteroids by mouth for a long time, thins the skin and can lead to stretch marks.
• Family history: the likelihood is higher in people whose close relatives have stretch marks.

If you notice stretch marks while using a corticosteroid cream, do not stop the medicine on your own; let the physician who prescribed it know. Your physician will decide how treatment should continue.

When does a stretch mark suggest an underlying condition?

In the great majority of cases there is no disease behind stretch marks. Rarely, an excess of the hormone cortisol in the body (Cushing's syndrome) or certain inherited conditions that affect connective tissue (for example Marfan syndrome) can show themselves through stretch marks. Seeing a physician is recommended in the following situations:

These signs do not amount to a diagnosis on their own; the assessment is made by examination and, if necessary, tests.

What is the difference between red and white stretch marks?

Stretch marks change stage over time. The stage you are at directly affects which method can be tried and how much change you can expect.

The spontaneous fading of red stretch marks is not healing but a change of stage: the colour lightens but the scar stays where it is. For this reason, the impression that a method has 'got rid of' a stretch mark is sometimes simply the result of natural fading. This is why comparing methods with placebo in studies is important.

Do stretch mark creams and oils prevent stretch marks?

A large number of creams, oils and lotions are sold for preventing stretch marks. A Cochrane review that examined products applied to the skin to prevent stretch marks in pregnancy assessed data from a total of 800 women in six studies and found no high-quality evidence that any of these products prevents stretch marks from forming. No statistically significant difference was found between those who used products with active ingredients and those who used placebo or nothing at all.

• Cocoa butter, olive oil, almond oil and vitamin E: in studies these did not prevent stretch marks or fade existing ones.
• Products containing Centella asiatica extract or hyaluronic acid: a preventive effect has been reported in some small studies; however, the evidence is limited and the results are not conclusive.
• Moisturising: can reduce dryness and itching in stretched skin. This gives some relief; it should not be expected to prevent stretch marks from forming.
• Tanning: does not remove stretch marks; because stretch mark tissue does not tan, the difference in colour may become even more noticeable. Self-tanning lotions, on the other hand, can temporarily conceal the difference in colour.

Prevention is not always possible. Keeping your weight as steady as possible is the only known general approach that can reduce the likelihood of stretch marks; how much weight you should gain in pregnancy, however, should be discussed with the physician who is following your pregnancy. For details relating to pregnancy, see the article “Medical Aesthetics in Pregnancy and Breastfeeding”.

Which methods have evidence?

The common conclusion of the reviews examining stretch mark treatment is this: many methods have been tried, some can reduce the appearance, but none removes a stretch mark completely, and strong evidence is scarce. Most of the studies are small and short-term and use different criteria.

Tretinoin is a prescription medicine; your physician decides whether it should be used, how often and for how long. It is not used in pregnancy; during breastfeeding and in those planning a pregnancy it should not be used without consulting a physician either. The same caution applies to retinol in cosmetic products.

Procedures carried out by a physician are generally accepted to be more effective than creams; even so, the expected result is not that the stretch mark is erased but that it becomes less noticeable. For details of the procedures, see the articles “Fractional Laser”, “Microneedling” and “Radiofrequency Skin Tightening and Radiofrequency Microneedling”. Because the risk of pigmentation after laser is higher in olive and darker skin, the article “Laser, IPL and Chemical Peels on Olive and Darker Skin” may also offer guidance.

What are the risks of the procedures?

Because stretch marks are a harmless condition, the risks of the chosen method should not be greater than the expected benefit. Redness and swelling are common after laser and needling treatments and mostly settle within days. Less commonly, darkening or lightening of the skin, burns, infection and scarring may develop. In people prone to raised scars, procedures that injure the skin should be assessed separately; on this subject, see the article “Scars and Keloids”.

Stretch mark treatment generally needs more than one session, and the results appear slowly. Be cautious about treatments that claim to erase stretch marks in a single session or to give a definite result.

Do stretch marks disappear completely?

No. A stretch mark is a type of scar, and no cream, device or procedure known today removes it completely. The realistic aim is for the colour to come closer to that of the surrounding skin and for the depression in the surface to decrease somewhat. The degree of change varies with the age and width of the stretch mark, the area it is in and skin colour.

• New stretch marks also fade on their own over time; even if nothing is done, they attract less attention over the years.
• The most suitable time for treatment is generally while the stretch mark is still red.
• With old, white stretch marks, no marked change should be expected from creams.
• The improvement achieved with procedures is modest; the striking differences seen in photographs may also be due to differences in lighting and angle.
• New stretch marks may form with changes in weight or a new pregnancy.

If you constantly feel bad about yourself because of your stretch marks, or restrict your clothing or social life because of them, it is helpful to talk about this openly with your physician. The article “Body Image and Aesthetic Treatments” may also help with this.