For patients with a rash, the effect of teledermatology workflow on utilization has not been defined. We compared utilization across four teledermatology workflows in patients with a rash. The observational longitudinal cohort study included 28,857 Kaiser Permanente Northern California members with a new rash diagnosis seen in primary care and with dermatology advice obtained using teledermatology. The workflows differed in camera and image quality; who took the picture; how the image was forwarded; and synchronicity and convenience. On average, 23% of patients had a follow-up office visit in dermatology within 90 days of their primary care visit. In multivariable analysis, the four technologies differed substantially in the likelihood of a follow-up dermatology office visit. In contrast, the likelihood was only negligibly related to medical centre or primary care provider. Technologies and workflows that offer the mobility of a smartphone with a high level of synchronicity in communication were associated with standardised co-management of rashes.