If you notice a rash developing in response to something you've put on your skin, wash your skin off with warm soap and water.  You may notice red skin, small, itchy bumps, tiny blisters, and/or warm skin.  Also wash anything else that came in contact with the irritant that you use regularly, such as your clothing. Though scratching is tempting, you should avoid it as much as possible. Scratching damages your skin, can make the rash worse, and possibly introduce infection. Because contact dermatitis is an allergic reaction, you can take an over-the-counter oral antihistamine pill, such as loratadine or cetirizine. Take these pills once a day to help manage symptoms. Just like atopic dermatitis, allergens and irritants can cause flare-ups, even if you inhale them or eat them. Try changing out your soaps and detergents to figure out what bothers you, and keep a food journal so you can make connections between what you eat and flare-ups. Remember that sometimes more than one factor may be causing your dermatitis. You may be affected by both your make-up and your sunscreen. In addition, sometimes the sun plays a factor, causing dermatitis in combination with another irritant. One way to help determine the source of your contact dermatitis is to do a patch test. Your doctor will apply patches of certain allergens and irritants to your skin, which you wear for 48 hours. When you go back to the doctor, she'll determine which ones you've reacted to, which can help you avoid allergens in the future. Once you figure out what causes your contact dermatitis, you will need to avoid that irritant in the future. For instance, if a particular detergent or soap causes your eczema, you will need to switch to other brands, preferably ones that are natural and fragrance-free. Moisturized skin is less likely to develop a flare-up. Additionally, moisturizers can help relieve the pain of flare-ups by softening cracked skin. Apply a thick moisturizer several times a day to your body to keep your skin barrier protected, which will...

TL;DR in Vietnamese:
Loại bỏ yếu tố kích ứng. Không gãi. Dùng thuốc kháng histamin. Loại bỏ yếu tố kích ứng và dị nguyên. Hỏi bác sĩ về xét nghiệm dị ứng áp da. Tránh dị nguyên và yếu tố kích ứng. Dùng sản phẩm dưỡng ẩm thường xuyên. Thử quấn ướt. Sử dụng kem steroid. Hỏi bác sĩ về thuốc uống corticosteroid.