Although it's best to prevent hair dye stains as much as possible by wearing gloves and applying dye carefully around the forehead, it can be difficult to avoid getting dye on your skin. Wiping off any spilled dye quickly and washing the area with soap and water can often prevent the dye from coloring your skin. If you end up with stains, there are a few home remedies, including toothpaste, dish soap mixed with baking soda and lemon juice, and nail polish remover, that will remove hair dye stains pretty quickly. Be careful not to get any of these removers on the dyed hair itself, as they can remove the color there too.
Prevention
The best way to ensure hair dye does not stain is to prevent it from getting on your skin as much as possible. Although hair coloring can be messy — especially when done at home — you can protect your hairline and neck by applying a thin, even layer of petroleum jelly or conditioner to the area. As these products are typically oil based, they prevent the dye from sticking to your skin and are easily washed off when you're rinsing the color from your hair. If the color does drip onto unprotected areas, wipe it off quickly with a damp cloth.
Toothpaste
While toothpaste does not seem to work on all skin types, it's a good first step since it is readily available, is relatively soft, and usually does not irritate or damage the skin. For this option, simply rub a small amount of toothpaste, preferably the kind that contains scrubbing granules, on the area until the stain lifts and then rinse with cool water.
Dish Soap, Baking Soda, and Lemon Juice
Mixing dish soap with either baking soda, lemon juice, or a combination of both can be an effective way to remove hair dye stains. The soap cleans the area, the baking soda provides scrubbing power, and the lemon juice acts as a bleaching agent. Mix equal parts of all three, and then rub this over the affected area until the stain is gone. Finish by rinsing with clean water. Some people recommend cigarette ash in place of the baking soda.
Nail Polish Remover
You can use nail polish remover to remove hair dye stains in small areas, but never use it near the eyes, nose, or mouth. To try it, soak a small ball of cotton with the remover and rub the stained area a few times until the dye lifts; in most cases, an acetone-based product works best. Always work in a well-ventilated area, as the fumes can be strong, and apply a light moisturizer after.
Bleach
It's usually not a good idea to use straight bleach on a hair dye stain, as it can be very damaging to the skin. If you have a particularly stubborn stain, a small amount on a cotton ball could be used to remove it. Be sure to wash the area thoroughly afterwards, and moisturize. Don't use bleach on the face or near the eyes.
Other Options
Other home products you can use to remove hair dye stains include rubbing alcohol, hydrogen peroxide, and aftershave; simply wet a cotton ball with any of these and rub it on the stain. While these products are effective, they should only be used on your hands, as getting any of these in your eyes can be painful and unsafe. Tea tree oil may also work, and many people recommend using baby wipes to clean up any drips. People with sensitive skin who need to remove hair dye stains should invest in a professional hair dye remover, which can be found in beauty supply stores and most hair salons.