What happens when a sebaceous cyst ruptures??

Depends. If it ruptures internally, it causes an inflammatory reaction. If it ruptures to the outside through a small opening the contents may dry up and grow like a horn, albeit very slowly, The rupture may allow the lesion to heal also. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex.