Stretch marks around the underarms and lower back are usually caused by stretching of the skin due to rapid weight gain or loss, growth spurts, bodybuilding, hormonal changes, pregnancy, or increased fat accumulation in certain areas of the body. They can also develop in people who use steroid creams for a long time or have certain hormonal conditions. Stretch marks are very common and harmless, but they may become more noticeable when they are new because they often appear reddish, pink, or purple before gradually fading over time. Keeping the skin well moisturised with gentle creams, lotions, cocoa butter, or oils may help improve skin texture and reduce dryness or itching. Maintaining a stable weight, eating a balanced diet rich in protein and vitamins, drinking enough water, and exercising regularly may also support skin health. Although creams can help improve the appearance slightly, stretch marks usually do not disappear completely on their own. If the marks are spreading rapidly, becoming painful, or associated with sudden weight changes or other health problems, it is best to consult a dermatologist for proper evaluation. Treatments such as laser therapy, microneedling, or chemical peels may provide further improvement in some cases.