Psoriasis is a stigmatized skin disease. This randomized controlled trial aimed to evaluate an Instagram based stigma-reduction intervention targeting daily Instagram users aged 18 to 49 years without psoriasis. After stratification for baseline characteristics (t0), stigmatization of psoriasis was assessed using a questionnaire and a photo-rating task immediately before (t1) and after (t2) the intervention and two weeks post-intervention (t3). Data from 54 participants, recruited in a university setting and via Instagram, were analysed. For 10 min between t1 and t2, the intervention group (n = 26) and the control group (n = 28) scrolled through two different Instagram accounts. Psoriasis-sensitizing content was displayed to the intervention group while beauty-glorifying posts were shown to the control group. Results indicated significantly less Disease-related Misconceptions in the intervention group in comparison to the control group at t2 (U = 145.50, Z = -3.79, p < 0.001) and at t3 (U = 177.00, Z = -3.25, p = 0.003). Moreover, the intervention group showed a significant reduction over time in Stereotype Endorsement (F(2, 50) = 13.40, p < 0.001, partial η² = 0.35) and Disease-related Misconceptions (χ2(2) = 12.64, p = 0.002). These findings suggest that addressing psoriasis on Instagram has the potential to effectively reduce the related stigmatization. Further studies are necessary to assess the impact of social media on stigmatization concerning psoriasis in more depth.