A dermatologist or dermatologic surgeon with training and experience in laser hair removal may be best suited to decide whether you’re a candidate for laser hair removal and, if so, what type of laser may work best for you. During an initial consultation, your doctor asks about your medical history, assesses your skin type and explains the risks and benefits of laser hair removal. To reduce the risk of complications, your doctor may ask you to refrain from taking medications such as aspirin and other nonsteroidal anti-inflammatory drugs, or dietary supplements such as niacin and vitamin E. If you have a tan from sun exposure or sunless tanning products, you must wait until the tan fades completely before you can undergo laser hair removal, because a tan increases your risk of side effects such as blistering and discoloration.

Laser hair removal is effective only on short, visible hair. Two to three days before the procedure, you shave the area to be treated, and allow it to grow to a stubble. Avoid waxing or plucking the hair. Ask your doctor about ways to minimize the discomfort of laser hair removal. He or she may advise you to apply a thick layer of an over-the-counter cream containing the anesthetic lidocaine to your skin 45 minutes before treatment.

Quoted from http://www.mayoclinic.com/health/laser-hair-removal/HQ00981