**1. Introduction**

Muscular pain is a very common pathology in the physiotherapy treatment of outpatient care. The invasive techniques for treating these patients have aroused great interest, there are many reviews made in recent years about its effectiveness but none with conclusive results [1–6]. Articles about post-needling pain [7, 8] and adverse side effects that may occur due to dry needling are being published until this day.

Dry needling is a minimally invasive technique into the most hypersensitive area/point of a tense band in a skeletal muscle (called myofascial trigger point), without the addition of any drug (**Figure 1**). It can be classified as deep or superficial [9]. There is not much evidence about which of the two options is better, it seems that deep dry needling has shown greater effectiveness due to penetrating the myofascial trigger point while the superficial dry needling penetrates the skin and the subcutaneous cellular tissue [10, 11]. In the same way, the appearance of local twitch response would guarantee its effectiveness [12, 13].

These myofascial trigger points present a high equivalence with the ashi points of acupuncture, corresponding to approximately 71% as Melzack introduced [14]. Acupuncture is based on a traditional and invasive Chinese technique of thousand years of age based on metaphysical concepts of "Ch'i" (Qi), the body energy flows through channels called "meridians" that has hypersensitive areas called ashi points

**Figure 1.** *Myofascial trigger point.*

**Figure 2.** *Acupuncture Meridians.*

*Needling Therapies in the Outpatient Care: Adverse Effects DOI: http://dx.doi.org/10.5772/intechopen.94774*

(**Figure 2**). Its treatment also consists in the insertion of a needle in these points without any type of drugs [15].

On the other hand, injections have also been the subject of many reviews, [16, 17] they have combined the effects of needling with the effect of local anesthetics. However, in 1943 Lewit [18] demonstrated that the true effectiveness of the infiltrations was due to the mechanical effect generated by the insertion of the needle itself and not the anesthetic.

The objective of this study is to summarize the articles published in relation to adverse effects of needling therapies to promote a good practice and knowledge.
