Stress, inadequate sleep, bingeing on greasy food, clogged pores, blackheads, sebaceous filaments are some of the common reasons that cause breakouts. Here are a few ways to tackle a sudden breakout:

Keep your skin oil-free and wash it at least twice a day even after a breakout. You can use a gentle face wash but make sure that your skin is squeaky clean.
Remove your makeup before going to bed. Use a good makeup remover that suits your skin. Going to bed with makeup will clog your pores and result in an ugly breakout. Let your skin breathe at night.

Regular exercise goes a long way. It not only helps one to cure breakouts but also prevents them from recurring.

Increase your water intake. Make it habit to drink a glass of water every two hours.
A no-touch policy helps. Touching the acne spreads infection and is extremely unhygienic.
Cover the tip of your acne with toothpaste before going to bed, keep it on overnight and wash it off in the morning. It will help in reducing the redness and make it smaller in appearance.