Pubic lice (otherwise known as crabs) are very small, parasitic insects which live on the pubic hair. They can be passed on during sexual contact, or through other close body contact like sharing towels or bed linen. Symptoms can take a few weeks to appear and include itching, irritation and inflammation -you may be able to see black powder (droppings), brown eggs or the actual lice Diagnosis involves a health professional examining the area to look for the crabs (which can grow to the size of a pin head) Treatment involves using lotion or shampoo. There’s not much you can do to prevent crabs, but they are easily treated and, aside from being incredibly itchy, are completely harmless Check out the NHS Choices website for more information about pubic lice. If you would like to know more about STI testing, check our Visiting a Clinic page.