**Abstract**

The invasive techniques have been used for many years. There is a lot of literature on the advances that have been made, as well as the adverse effects or possible complications that have occurred during the performance of these treatments. Acupuncture and injections (saline, anesthetics, corticosteroids or botulinum toxin) have reported several cases of complications. Dry needling is also beginning to have several publications of this type. The objective of this chapter is to summarize the articles published in relation to adverse effects of needling therapies to promote a good practice and knowledge. Original articles in form of randomized controlled trials, case reports and reviews relating adverse effects and possible complications due to invasive/needling techniques: acupuncture, injections and dry needling have been included. 102 articles met the inclusion criteria between January 2000 and January 2020. The first limitation found in the literature was the huge variety of cases, therapists and incidents to generalize. As a conclusion we can stated the importance of a good knowledge of the anatomy and its variants, the correct application of these techniques and a continuous training of these therapists must be essential.

**Keywords:** dry needling, acupuncture, injection, adverse effect, safety
