7 DRUG INTERACTIONS 7.1 Concomitant Therapies In plaque psoriasis trials the safety of ustekinumab products in combination with immunosuppressive agents or phototherapy has not been evaluated. In psoriatic arthritis trials, 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-hmny