Stretch Marks: Causes, Prevention, and Treatment

What stretch marks actually are and where they start

Stretch marks, clinically known as striae distensae, are a form of dermal scarring. They develop when the middle layer of skin (the dermis) is stretched beyond its capacity to recoil. The dermis is held together by collagen and elastin fibers, proteins that give skin its strength and flexibility. When skin expands or contracts rapidly, these fibers rupture. As the skin attempts to repair itself, it lays down scar tissue that appears as streaks or lines on the surface.

Early stretch marks, called striae rubrae, are red or purple because blood vessels in the dermis are visible through the thinned skin. Over time, as inflammation subsides and blood vessels contract, they fade to white or silver, becoming striae albae. This color change reflects the maturation of scar tissue, not healing. The structural damage remains. The skin in these areas is thinner, less elastic, and lacks the normal texture of surrounding tissue.

Stretch marks most commonly appear on the abdomen, breasts, hips, thighs, buttocks, and upper arms. These are areas where skin is under the most tension during periods of rapid growth or weight change. They're not caused by poor hygiene, lack of hydration, or surface-level skin issues. They're the result of a mechanical and biochemical breakdown in the dermis.

How hormones, mechanical stress, and skin structure drive stretch marks

Stretch marks don't happen in isolation. They're the visible result of internal processes that weaken the skin's structural integrity. Hormones play a central role. Cortisol, the body's primary stress hormone, directly weakens collagen and elastin fibers. Elevated cortisol levels (whether from chronic stress, pregnancy, or conditions like Cushing's syndrome) make skin more vulnerable to tearing under tension.

During pregnancy, estrogen and progesterone surge. These hormones alter collagen production and skin elasticity, making the dermis more prone to rupture as the abdomen expands. Adolescents going through puberty experience similar hormonal shifts, particularly increases in growth hormone and sex hormones, which can outpace the skin's ability to adapt.

Mechanical stress is the other half of the equation. When skin is stretched rapidly, the dermis doesn't have time to produce new collagen and elastin at the rate needed to maintain structural integrity. The fibers snap. This is why stretch marks are so common during pregnancy, puberty, and periods of rapid weight gain or loss.

Corticosteroid use, whether topical or systemic, also increases risk. These medications suppress collagen synthesis and thin the skin over time, making it less resilient. Long-term use of high-potency topical steroids or oral corticosteroids for conditions like asthma or autoimmune disease can trigger stretch marks even without significant weight change.

What triggers stretch marks and why the same thing doesn't affect everyone

Stretch marks are triggered by rapid changes in body size, but the specific inputs vary:

• Pregnancy affects up to 90% of women, particularly in the third trimester when abdominal expansion accelerates.
• Puberty is a high-risk period, especially for adolescents experiencing growth spurts.
• Weight gain (whether from increased muscle mass or fat) stretches skin quickly.
• Weight loss can trigger stretch marks if skin contracts faster than the dermis can remodel.
• Hormonal conditions like Cushing's syndrome, thyroid dysfunction, or PCOS alter skin structure and increase susceptibility.

Nutritional deficiencies can also play a role. Vitamin D deficiency has been linked to higher rates of stretch marks, possibly because vitamin D influences skin regulation and collagen synthesis. Low levels of zinc, vitamin C, and protein (all essential for collagen production and skin repair) may reduce the skin's ability to withstand stretching.

Do stretch marks itch? Yes, and itching is most common when they're actively forming. The itching reflects nerve stimulation as the dermis tears and inflammation sets in. The skin in these areas is thinner and more sensitive, leaving nerve endings exposed. Dryness can worsen the itch, but the underlying cause is the structural damage itself, not just surface dehydration.

Why the same condition looks different and responds differently in different people

Genetic factors

Not everyone who gains weight or goes through pregnancy develops stretch marks. Genetics are the strongest predictor. If your parents or siblings have stretch marks, you're more likely to develop them. Specific gene variants affect collagen and elastin production, skin thickness, and how skin responds to mechanical stress. Filaggrin gene mutations (which are also linked to eczema) can compromise skin barrier function and increase susceptibility.

Skin characteristics and hormonal baseline

Skin type and baseline collagen density also matter. People with naturally thicker, more elastic skin are less prone to stretch marks. Skin phototype influences presentation: stretch marks may appear darker or more pigmented in individuals with higher melanin content, particularly during the red phase, due to post-inflammatory hyperpigmentation.

Hormonal baseline varies widely. Some individuals produce more cortisol in response to stress or have higher baseline levels, making their skin more vulnerable. Estrogen and progesterone levels during pregnancy differ, which may explain why some women develop extensive stretch marks while others don't, even with similar weight gain. Age at the time of stretching also plays a role. Younger skin has more collagen and elastin and is generally more resilient, but it's also undergoing rapid growth, which increases mechanical stress.

Stretch marks vs cellulite and what each one tells you

Stretch marks and cellulite are often confused, but they're fundamentally different. Stretch marks are dermal scars caused by collagen and elastin rupture. Cellulite is a structural issue involving fat distribution, connective tissue architecture, and how fat cells push against the skin. Cellulite creates a dimpled, uneven texture, often described as resembling cottage cheese or an orange peel. Stretch marks are linear streaks or bands.

Cellulite involves the subcutaneous fat layer and the fibrous septae that connect skin to underlying muscle. When fat cells enlarge or fibrous bands tighten, they pull down on the skin while fat pushes up, creating the dimpled appearance. Stretch marks, by contrast, are purely dermal. They don't involve fat tissue directly, though rapid fat gain or loss can trigger them.

Cellulite is more common in women due to differences in fat distribution, connective tissue structure, and hormonal influences. Estrogen affects fat storage and connective tissue elasticity, making cellulite more prevalent after puberty and during hormonal shifts. Stretch marks affect both sexes, though they're more common in women due to pregnancy and hormonal fluctuations. Treatment approaches differ. Cellulite responds to therapies that target fat and connective tissue (like radiofrequency, acoustic wave therapy, or subcision). Stretch marks require treatments that stimulate collagen remodeling in the dermis (like laser therapy, microneedling, or topical retinoids).

When stretch marks point to something systemic

Most stretch marks are benign and reflect normal physiological changes. But in some cases, they signal an underlying condition worth investigating. Rapid, unexplained stretch mark formation (especially in someone who hasn't experienced significant weight change or pregnancy) can indicate elevated cortisol levels. Cushing's syndrome, caused by prolonged exposure to high cortisol, produces wide, purple stretch marks, often on the abdomen, thighs, and upper arms. These are typically more severe and appear without the usual triggers.

Stretch marks in adolescents who aren't going through a growth spurt or weight change may warrant evaluation for hormonal imbalances. Conditions like PCOS (which involves elevated androgens and insulin resistance) can present with stretch marks alongside irregular periods, acne, and weight gain. Thyroid dysfunction, particularly hypothyroidism, can alter skin texture and collagen production, indirectly increasing stretch mark risk.

Prolonged corticosteroid use (whether oral or topical) is a known cause of stretch marks. If you're using high-potency topical steroids for eczema or psoriasis, or taking oral steroids for asthma, autoimmune disease, or other conditions, stretch marks may develop even without weight change. This is a signal to discuss dosing and duration with your provider. Nutritional deficiencies, particularly in protein, vitamin C, vitamin D, and zinc, can impair collagen synthesis and skin repair.

What biomarkers can tell you when stretch marks keep appearing

If stretch marks are forming without clear triggers, or if they're more severe than expected, testing can surface underlying drivers:

• Cortisol levels (measured via serum or 24-hour urine collection) can identify Cushing's syndrome or chronic stress-related elevations.
• Insulin and HbA1c can flag insulin resistance, which is linked to PCOS and metabolic changes that affect skin health.
• Thyroid function (assessed through TSH, free T3, and free T4) can reveal hypothyroidism or hyperthyroidism, both of which alter skin cell turnover and collagen production.
• Thyroid peroxidase antibodies can identify autoimmune thyroid disease.
• Nutrient markers like vitamin D, zinc, and vitamin C can identify deficiencies that impair collagen synthesis.
• Ferritin and iron status can reveal anemia, which affects tissue repair.
• High-sensitivity C-reactive protein can indicate systemic inflammation, which may impair skin healing and collagen remodeling.

For women with suspected PCOS, testing total testosterone, free testosterone, SHBG, and LH/FSH ratio can clarify hormonal imbalances. Tracking these markers over time (especially during periods of weight change or hormonal shifts) provides a clearer picture of what's driving skin changes.

What treatments actually work and what the evidence shows

Topical treatments

Tretinoin, a prescription retinoid, is the only topical agent with consistent evidence for improving early stretch marks. It works by stimulating collagen production and increasing skin cell turnover. Studies show tretinoin can improve the appearance of red stretch marks, but it's less effective on mature, white stretch marks. It's contraindicated during pregnancy. Over-the-counter creams containing hyaluronic acid, centella asiatica, or vitamin E may improve hydration and reduce itching, but they don't reverse the structural damage. Cocoa butter, despite its popularity, has no strong evidence for preventing or treating stretch marks.

Laser therapy and microneedling

Laser therapy is the most effective treatment for mature stretch marks. Fractional CO2 lasers and fractional radiofrequency microneedling stimulate collagen remodeling by creating controlled micro-injuries in the dermis. Multiple sessions are typically required, and results vary based on stretch mark age, skin type, and individual healing capacity. Pulsed dye lasers can reduce redness in early stretch marks by targeting blood vessels.

Microneedling (which uses fine needles to puncture the skin and trigger collagen production) shows promise, particularly when combined with topical treatments or platelet-rich plasma (PRP). Studies suggest microneedling can improve texture and pigmentation, though it's less effective than laser therapy for deep, mature stretch marks. No treatment fully erases stretch marks. The goal is to improve texture, reduce contrast with surrounding skin, and stimulate collagen remodeling. Early intervention (when stretch marks are still red) yields better results than waiting until they've matured to white.

Turning skin symptoms into a systemic investigation

Stretch marks are common, but persistent or unexplained formation is worth investigating. If you're developing stretch marks without clear triggers like pregnancy, weight change, or puberty, or if they're appearing alongside fatigue, mood changes, or other systemic symptoms, testing can identify hormonal imbalances, nutrient deficiencies, or metabolic dysfunction. Superpower's 100+ biomarker panel measures cortisol, insulin, thyroid function, vitamin D, and inflammatory markers, giving you a clearer picture of what's happening beneath the surface. Stretch marks are information. Tracking the internal drivers over time helps you understand whether they're a normal response to growth or a signal of something that needs attention.