Background

Laser therapy is the use of amplified beams of light called lasers to diagnose or treat medical conditions. The word laser is an acronym for "light amplification by stimulated emission of radiation."

The laser involves exciting atoms and passing them through a medium such as crystal, gas, or liquid. As the cascade of photon energy sweeps through the medium, bouncing off mirrors, it is reflected back and forth. It gains energy to produce a high-wattage beam of light.

Lasers have four main parts: the active medium, the excitation mechanism, the feedback mechanism, which is usually a reflective mirror, and the output coupler.

Lasers are named for the liquid, gas, solid, or electronic substance that is used to create light. Lasers that have carbon dioxide gas as the medium are often used for snoring or for cosmetic resurfacing, such as to smooth out skin damaged by acne. The strength of the laser light determines how it is used in medicine.

Laser light differs from the natural light of the sun since it is a controlled emission rather than a spontaneous emission. Therefore, unlike natural light, light beams from lasers have the same wavelength and travel in one direction and therefore can be targeted.

Lasers have been used in various medical conditions, removal of tattoos, hair growth, hair removal, surgical procedures, acupuncture, and cosmetic procedures. Lasers are also commonly used in eye surgeries such as laser-assisted in situ keratomileusis (LASIK), laser epithelial keratomileusis (LASEK), and cataract and eye tumor removal.

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Effectiveness Effectiveness definitions

Laser therapy includes a wide group of modalities and treatments such as LASIK, laser acupuncture, and laser hair removal. See specific modality and treatment monographs for further effectiveness information.

Breast cancer. Some clinical research suggests that laser therapy may reduce the size of breast cancer mass, improve subjective symptoms, and improve quality of life in women.

Diabetic retinopathy. Some clinical research shows that laser therapy (where the laser is directed toward the retina) may reduce the chance of vision loss by 50% compared to no treatment and may help improve macular edema.

Neck pain. Some research shows that low-intensity laser therapy may be effective in reducing neck pain and allow patients to remain pain free for up to 22 weeks.

Tendinopathy. There is conflicting clinical evidence on the efficacy of using low-level laser therapy for improving tendinopathy or tendon injury.

Varicose veins. Some clinical research suggests that laser therapy may reduce pain from varicose veins for two years in up to 90% of treated patients. More evidence is needed to rate laser therapy for these uses.

Natural Medicines rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

Dosing & administration

Adverse effects

General: Laser therapy includes a wide group of modalities and treatments such as LASIK, laser acupuncture, and laser hair removal. See specific modality and treatment monographs for further effectiveness information.

Interactions with pharmaceuticals

None known.

Interactions with herbs & supplements

None known.

Interactions with foods

None known.

Interactions with lab tests

Interactions with diseases

Mechanism of action

The use of lasers for many medical procedures is well established. Lasers are beneficial because they are more precise than other instruments, such as scalpels, used during surgery. In addition, certain healthcare professionals claim that there may be less scarring with lasers, the procedure may take less time, and the healing time may be faster.

Theoretically, lasers stimulate molecules that are part of cells' transport mechanisms. These molecules are found on the surface of the cells, directly inside the outer membrane of the cell, and inside the mitochondria. In theory, this may improve blood flow, stimulate new cell growth by increasing DNA and RNA synthesis, increase antioxidant production, normalize tissue's acid-base balance, and increase the rate at which the body makes energy as adenosine triphosphate (ATP).

There are two major types of lasers, contact and noncontact, used for therapeutic purposes. Contact lasers work by sending a light through a fiber or sapphire tip. The tip absorbs energy and becomes hot. When the hot tip touches any live tissue in the body, the target cells are vaporized, which is the removal of tissue through the conversion of a solid to a gas. Noncontact lasers do not touch the tissue. They operate by transferring laser light as radiant energy in a single beam to the tissue. Heat results when the cell absorbs this energy. In both cases, the laser light is not hot. Heat is only created after the laser's radiant energy is absorbed by the targeted tissue.

Contact lasers can be used for cutting through bone as well as pulverizing kidney stones. A common contact laser is called the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. This laser can go deep into the tissue and even cause blood to clot. It is often used in cancer patients.

Some noncontact lasers are used with laser light-sensitive drugs. Such a drug is administered to a patient, and over time, the drug is targeted to be absorbed only into tumor cells. By exposing the drug in the cancer cells to the laser, a chemical reaction occurs. This theoretically kills the cancer, but not the healthy cells.

Theoretically, low-intensity laser therapy may stimulate the growth of bone marrow stem cells. These stem cells in theory may help treat a variety of diseases, such as cancer and chronic obstructive pulmonary disease (COPD). Thus, laser therapy may contribute to the new field of regenerative medicine.