Better safe than sorry (really sorry)...
In adults, phimosis can occasionally be associated with sexually transmitted infections (STIs). It can also be caused by a number of different skin conditions including:
eczema – a long-term condition that causes the skin to become itchy, red, dry and cracked
psoriasis – a skin condition that causes red, flaky, crusty patches of skin covered with silvery scales
lichen planus – a non-infectious itchy rash that can affect many areas of the body
lichen sclerosus – a scarring condition of the foreskin (and sometimes glans) that's probably caused by urinary irritation in susceptible men and boys