Mesotherapy Injections are usually given with tiny small-bore needles. The injections go to a depth of a few millimeters below the skin, to a layer of fat and connective tissue called the mesoderm. Patients describe Mesotherapy Injections as being relatively painless when compared to conventional injections. The amount of pain felt depends on each patients pain threshold and whether a local anesthetic is used during the procedure. Injections are said to feel like a brief burning sensation, an ant bite, or a bee sting. The number of injections given depends on the duration of treatment, which in turn depends on the area being treated and the extent of the condition. Most mesotherapy treatments range from four to ten sessions. Each session is typically one to two weeks apart.

Compounds that are injected depend on what condition is being treated. Very often, mesotherapists add the active compound to treat a particular condition to a base containing local anesthetic and a compound that causes blood vessels in the area to dilate. This helps reduce pain, and improves local circulation in the area to allow the active compound to reach its target cells. The actual compounds themselves may be fat reduction agents, vitamins, muscle relaxants, enzymes, hormones, or some other substance. While the US Food and Drug Administration has approved most of these compounds for use on humans, they are not approved for use in mesotherapy because mesotherapy itself is not considered a formal part of allopathic medicine in the US.

Like any other injections, Mesotherapy Injections carry the risk of side effects including infection, local allergic reactions, bruising, swelling and pain. Infections are usually caused by non-sterile injection practices, and are more common among patients of unlicensed mesotherapy practitioners.