Background Many therapists practise PC6 acupuncture for emesis (nausea and vomiting) during pregnancy, different cancer therapies, palliative care, after surgery, or to induce relaxing effects in general. Knowledge of side effects is central to shared decision-making. Aim To describe the type and frequency of side effects and the level of needle-induced pain during PC6 acupuncture. Methods We included 1298 PC6 acupuncture treatments, delivered to 221 participants (77% women, mean age 52.5, range 18-91 years). The subjects had received genuine PC6 acupuncture, in one of two previous randomised controlled trials, aimed at inducing antiemetic (n=100, with 100 providing data on side effects and 94 on needle-induced pain, respectively) or relaxing (n=121, with 120 providing data) effects. Side effects during and after the acupuncture treatments were registered in structured treatment protocols and study diaries. Results No serious complications occurred. Side effects during the acupuncture sessions included minor bleeding in 5.0%, tiredness in 4.9%, numbness in 4.5% and dizziness in 1.4% of the 1298 treatments. After treatment, the mean proportions of participants reporting side effects each week were: tiredness 25.8%; feeling cold 17.8%; dizziness 9.7%; sweating 9.3%; haematoma 8.8%; and soreness at the needling sites 4.3%. Participants perceived the needling to be not painful (47.4% of participants), or mildly (39.1%), moderately (11.6%) or very painful (1.4%). Conclusions Few side effects occurred and those that did were mild. Nearly 90% found PC6 acupuncture to be not painful or only mildly painful. Healthcare professionals may consider the observed levels of side effects when informing patients about side effects of PC6 acupuncture.