Pimples that pop up long past the teenage years are just, well ... unfair.
"Hormonal changes and using the wrong skin care products are common causes," says Dr Melissa Schwarzschild, a dermatologist with Richmond Dermatology & Laser Specialists in the US.
But you can fight back:
* Wash your face every night: Oil, dirt and sweat build up in skin pores and can lead to pimples. That's true for women - especially those who wear make-up - and men, who naturally produce more oil. Also aim to shower soon after exercise.
* Exfoliate regularly: Remove dead skin cells at the skin's outermost surface once or twice a week. Use a low strength glycolic acid or mild facial scrub.
* Buy 'non-comedogenic' skin care products: These lotions, cleansers, cosmetics, soaps and sunscreens are formulated not to block pores and trap in oil. 'Water-based' and 'oil free' are other good words to look for on labels.
* Try to balance out hormones: Just before menstruation, a woman's estrogen levels decrease and the hormone progesterone becomes dominant, which can trigger breakouts. Several types of birth control pills can make a difference.
* Manage rosacea: This facial skin condition, marked by redness from broken blood vessels, is the most common cause of adult acne. Sun, heat, alcohol and spicy foods can trigger flare-ups, as can not wearing sunscreen daily. A dermatologist also can help with treatment.
* Touch your face less often: Your hands pick up bacteria and dirt throughout the day - no matter how often you wash up - which you can transfer to skin on your face.
* Control strress: Anxiety increases the hormone cortisol, which in turn triggers sweat glands in your face to produce more oil. Get enough sleep, exercise regularly, eat well, drink lots of water and find ways to relax.