7 DRUG INTERACTIONS 7.1 Concomitant Therapies In trials in subjects with plaque psoriasis, the safety of ustekinumab products in combination with immunosuppressive agents or phototherapy has not been evaluated. In trials in subjects with psoriatic arthritis, concomitant MTX use did not appear to influence the safety or efficacy of ustekinumab. Use of these concomitant therapies did not appear to influence the overall safety or efficacy of ustekinumab.
Source: FDA drug label - ustekinumab-srlf