Low level lasers are also called cold lasers. They do not produce any heat, therefore no damage occurs. You typically will not feel anything. The effects and results may be immediate and are cumulative. 

Lasers produce photons of energy. These energy packets go to the cells and bind on receptor sites; just as a medication would. This causes the cell to produce more energy, Adenosine Triphosphate (ATP). This is the energy that our bodies run on. This is the energy our food it turned into. When cells have more energy, they function at a higher level and promote restoration. Pain and inflammation may be decreased, blood flow may be increased and tight muscles can relax. 

Over time the benefits are systemic or occur throughout the whole body. It would be similar to putting a few drops of food coloring in a glass of water. Eventually it will disperse. The positive effects of LLLT progressively do the same throughout the body. Laser treatments are typically 10-20 minutes in length. There is no need to disrobe. LLLT is most effective on exposed skin but will work effectively through clothing. 

 Most people will feel nothing but sometimes a slight tingle or sensation is felt. Often an improvement in condition is immediately felt but occasionally it is later that day or the next.