IL17A and Opportunistic infection: Phase 2 and 3 studies on anti-IL-17 and anti-IL-23 did not show any increased risk of serious infections [105,106]; however, post-marketing studies highlighted an increased risk of opportunistic infections such as esophageal candidiasis, herpes zoster, pneumonia, and even Mycobacterium avium complex infections, especially with the use of anti-IL-23 drugs [107].