Nicotine stains in a smoker's moustache are unattractive. The tar from exhaled smoke leaves a brownish stain that is difficult, but not impossible, to remove. Here are several ideas that will help.
Use scissors to trim as much of the tar-stained hair as possible off the moustache. Use a clarifying shampoo to wash the entire moustache. Repeat this several times. It will reduce some, if not all, of the staining.
Liberally apply a smoker's toothpaste to the moustache hair and allow it to sit for several minutes. You may also add baking soda to the toothpaste because soda boosts the bleaching power. Repeat until the stains diminish.
Hydrogen peroxide is a mild bleaching agent. Do not confuse this with the type of peroxide used in head hair-lightening products. Brush on the hydrogen peroxide with a clean toothbrush and allow it to sit for several minutes before rinsing. Sitting in the sun may accelerate the bleaching process.
If stains remain in the moustache hair, use bleach for facial hair. It is a cream applied to the moustache hair that will lighten all of the hair, so apply only to the stained area. Follow directions on the package for application and length of time for each application.
If stain persists, apply moustache colouring. Follow instructions on the package for application.
Shave off the moustache and begin again. Avoid exhaling cigarette smoke through the nostrils and carefully shampoo and rinse the moustache hair after every cigarette.
Do not use household bleach or regular hair bleach because it may damage your skin.