Cho, your acne is most likely hormonal, as you are only 13 years old. Acne is a sign that something on off kilter internally. In the event that it is not caused by your hormones, you may want to look at your diet. It could be a sign of deficiencies. Vitamin A is good for clearing your skin. It reduces the oxidation of DNA and disables reactive oxygen molecules to prevent skin damage. Vitamin A is fat-soluble and can be toxic in high doses. Too much can be very taxing on the liver , so I would recommend getting it from natural sources such as sweet potatoes, carrots, spinach, etc… You basically want to eat your brightly colored fruits and veggies (orange, red and green). Zinc is beneficial as it boosts the immune system. It is also necessary for assimilation of vitamin A. Vitamin E is an antioxidant that is good for tissue repair. Vitamin C boosts immune function and reduces inflammation. Selenium is an antioxidant that improves tissue elasticity. EFAs will help soften and smooth the skin and dissolve fatty deposits that block your pores. Fresh garlic can enhance your immune system by destroying harmful bacteria. Just cut a fresh clove into pill size pieces and swallow them whole. Make sure you are getting enough fiber in your diet. Also, drink plenty of water to flush the toxins from your system. Our skin is the largest organ of the body. One of its functions is eliminating toxic waste products by sweating. When your body has more toxins than what your liver and kidneys can handle, they are secreted through the skin. Dandelion root (one of my favorite herbs) and milk thistle are good for detoxification, although, at your young age, I would advise against this until you speak to a doctor. Even though you don’t need prescriptions for herbs, some of them are quite powerful and can have dangerous side effects. Acne can also be caused by overly dry skin. Gentle exfoliation will help remove the dry, dead skin cells that could be blocking your pores. A good clarifying lotion can sweep away the top layer and allow your healthy skin to breath. I personally love Clinique products. Make sure you are using an oil-free moisturizer after you wash and exfoliate. Try not to wash your face more than twice a day.
Please do not go out and buy a hundred different vitamin and mineral supplements. I told you which ones are good for your skin, so now you need to do your research and find out which foods have the highest concentrations. You have your homework cut out for you.
There is one more thing I would like to add. Overcooking your vegetables can destroy their nutrients, so I would recommend eating them raw or only slighly cooked and try to avoid microwaving at all costs.