JAK inhibitors are a group of drugs that can affect the signaling of various cytokines simultaneously. The number of indications in dermatology has been increasing in recent years. JAK inhibitors are largely metabolized by the liver. Therefore, drug–drug interactions may occur when used with cytochrome P450 and CYP2C19 inhibitors or inducers, and drug dosages should be adjusted or not used together. In addition, OAT-3 inhibitors, which are known to play a role in renal elimination, interact with some JAK inhibitors, and dose adjustment is recommended. During treatment, drug–drug interactions should be reviewed in combination with JAK inhibitors and other drugs.