Bulging veins aren’t always dangerous, but they can sometimes signal an underlying health issue. Understanding why veins become more visible is key to recognizing when to seek medical attention.

Common causes include excessive exercise, aging, hot weather, tight clothing, genetics, sun exposure, and being overweight. In many cases, they’re harmless, but medical advice is recommended if veins show discoloration.

Bulging often occurs when blood pools in weakened or damaged veins instead of flowing smoothly back to the heart. This can lead to varicose veins — swollen, twisted veins most common in the legs but also found in the arms.

According to the Cleveland Clinic, smoking, obesity, genetics, hormonal changes (especially during pregnancy), and long periods of standing or sitting are primary contributors to varicose veins.

Treatment depends on severity. Doctors may recommend injection therapy, leg elevation, compression stockings, or in more serious cases, vein surgery.

If left untreated, varicose veins can cause venous ulcers — slow-healing open wounds near the ankles caused by poor circulation.

They can also increase the risk of blood clots, which may lead to pulmonary embolism, superficial thrombophlebitis, or deep vein thrombosis, all of which require urgent care.

While not always preventable, the risk of varicose veins can be reduced through regular exercise, maintaining a healthy weight, quitting smoking, and wearing loose clothing, especially around the waist.