Skin Allergy Test: With soap and water, wash an area the size of a quarter in the bend of your elbow. Pat dry with absorbent cotton. Apply product to test area, using an absorbent cotton-tipped applicator. Leave on for 5-10 minutes and rinse off. et test spot dry. Examine test area periodically over the next 12-24 hours. If you experience any reactions - such as redness, burning, itching, swelling, skin abrasion, eruptions or irritation in or around the test area, you should NOT use product until after consulting a doctor. If you experience any such reaction during application, rinse immediately and consult a doctor. You should NOT use hair color again until after consulting a doctor.