The Workup Before Initiating a JAK Inhibitor for Alopecia, With David Cotter, MD, PhD

Before prescribing a patient with alopecia areata a JAK inhibitor, what should you do? At the 2025 Society of Dermatology Physician Assistant (SDPA) annual summer meeting in Washington, DC, HCPLive spoke with David Cotter, MD, PhD, an assistant clinical professor at the University of Nevada, on the workup before initiating a JAK inhibitor for alopecia areata, key safety concerns for JAK inhibitors, and his perspective on JAK inhibitor use in younger patients.

“I hope that when people leave my talk that they have some tools to use when they get back to [the] clinic on Monday, [and] they feel comfortable prescribing JAK inhibitors,” Cotter said. “There's nothing wrong with reaching for them. It's so easy. You check some baseline labs… [and] if everything looks good at baseline, you start the medicine, and you can see your patient back in 4to 12 weeks and recheck labs. Usually by the 12-week mark, you're high-fiving because there's really clinically meaningful hair regrowth.”

For Cotter, the workup before initiating a JAK inhibitor for alopecia areata consists of a Comprehensive Metabolic Panel (CMP), fasting lipids test, checking for latent TB infection and hepatitis B serologies, and QuantiFERON gold. Patients may also receive a pregnancy or an HIV test. In Cotter’s practice, he also checks for varicella zoster (VZD) virus antibody titers.

“That's outside of the JAK guidelines, but I like to know if my patients are already immune to VZD, because when I think about all of the side effects of a JAK inhibitor, that keep me up at night,” Cotter said.

Cotter also recommends that individuals get a single vaccine. Still, he checks their baseline titers to see if they are immune to shingles at baseline, so he is aware of the odds of shingles reactivation.

Even after completing the proper workup before initiating JAK inhibitors, Cotter emphasized the importance of follow-up with repeat labs in a period of 4 – 12 weeks.

“What we do in our practice is we check patients at the 12-week mark, and we'll recheck their blood counts by ordering a CBC with [differential],” Cotter said. “We'll check liver function tests and fasting lipids. If everything is normal at the 12-week mark, we'll space those labs out to anywhere from Q6 to Q12 months, depending on the patient's baseline risk. So, a healthy 14-year-old who has no other medical complications, we'll check those labs annually, but say an 80-year-old chain smoker with cardiovascular risk factors, we're going to be checking those labs every 3 months.”

References

Cotter, D. Hair Loss Track: JAK-ing Up Alopecia Areata. Presented at the 2025 SDPA annual summer meeting 2025 on June 27th.