Skin patch tests can detect delayed allergic reactions, which can take from several days up to a week or more to completely develop. That is why you may be asked to return several times to the office for the staff to examine the testing site. During the skin patch test, depending upon the reason for test, the skin will be exposed to a number of different substances that can cause contact dermatitis. These substances may include medications, fragrances, latex, preservatives, hair dyes, resins, and metals. You will be requested to wear the skin patches on one of your arms or back for 48-72 hours. During this time, we ask that you avoid bathing and enjoying activities that can cause heavy sweating. The skin patches will be removed when you come back in for your follow-up appointment at our clinic. Areas of redness and swelling may indicate a positive reaction.