While styes (hordeolums) normally get better without treatment, they may cause some complications. These are rarely serious.
If you have a long-term stye on the inside of your eyelid (internal stye), this can develop into a Meibomian cyst. Meibomian cysts are also called chalazions. A Meibomian cyst can develop if one of the Meibomian glands on your eyelid becomes blocked.
Cysts are normally painless unless they get infected. In this case, you may need to take antibiotics (medication to treat bacterial infections).
Applying a warm compress (a cloth warmed with hot water) to the cyst should help bring the cyst down, although most cysts disappear by themselves. If a cyst does not disappear, it can be removed with a simple surgical procedure carried out under local anaesthetic (the area is numbed).
If the infection that caused your stye spreads to the tissues around your eye, it can cause preseptal cellulitis. Preseptal cellulitis, also known as periorbital cellulitis, is inflammation (redness and swelling) in the layers of skin around your eye. It can make your eyelids swollen and red.
Preseptal cellulitis can be treated with antibiotics. For more information about this condition, see the Health A-Z topic about Cellulitis.