In a study appearing in the January 2014 issue of the Journal of the American Academy of Dermatology, researchers tested 2,453 people and found that those who had atopic dermatitis, or eczema, were more likely than people without eczema to have an allergic reaction to certain ingredients in topical products. The reaction—allergic contact dermatitis—can result in a rash or red, itchy, swollen skin, sometimes with blisters.

The allergens in the study that caused the reactions were cosmetic preservatives called formaldehyde releasers. Formaldehyde releasers are designed to take advantage of the bacteria-preventing benefits of formaldehyde while bypassing the chemical’s adverse effects such as skin irritation and the possibility that it may play a role in cancer development. If you have eczema, help prevent reactions by trying these tips:

Avoid skin-care products containing the following formaldehyde releasers: quaternium-15; imidazolidinyl urea; DMDM hydantoin; 2-bromo-2-nitropropane-1,3-diol; and diazolidinyl urea. Exposure to paraben preservatives, such as methyl, ethyl, propyl, and butyl paraben, did not cause any allergic reaction in people with eczema in the study.

Choose products with a low water content—for example, ointments, since they usually contain no preservatives—if you have mild eczema and are looking for relief.

Pick parabens over formaldehyde releasers if you opt for a lotion, cream, or other product that contains preservatives.

Apply a moisturizer within three minutes of a short, warm— not hot—shower or bath using mild, unscented soap. (Pat, don’t rub, skin dry with a soft towel first.)

See a dermatologist if your eczema is chronic, severe, or not relieved by over-the-counter products. He or she can help you sort through skin-care options and prescribe treatment to help relieve inflammation.