Many trials examining phosphatidylserine (PS) do not comment on adverse events.[1][2][3][4][5][6][7][8] However, in the trials that do, there does not appear to be a significantly increased risk of adverse events compared to the control group.[9][10][11][12]
Four randomized controlled trials (RCTs) of PS in adults over age 50, using dosages of 300–600 mg per day over periods of 3–6 months, did not note any significant increase in adverse effects in the PS groups compared to the control groups.[9][10][11][12] Similarly, a 15-week trial of PS in children with ADHD observed no major adverse events in the participants given PS, although there were some cases of gastrointestinal discomfort.[13] One of the trials in older adults noted that any PS-associated gastrointestinal discomfort may be minimized by consuming PS with food.[12]
While several RCTs have examined PS supplementation in athletes,[1][2][3][4] they did not comment on adverse events; it's worth noting that three of these studies used high dosages of PS (600 mg or 750 mg per day) for shorter durations (7 to 10 days).[1][2][3] Likewise, of three RCTs of PS in people with chronic stress,[6][14][7] only one study commented on adverse event rates; that study, which had 60 total participants, only noted 2 adverse events among participants taking PS, compared to 9 adverse events in the participants who took a placebo.