 David Cotter, MD, PhD

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

, an assistant clinical professor at the University of Nevada, on the workup before initiating a JAK inhibitor for 

, 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.”

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

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JAK Inhibitors Show Promise Across Alopecia Subtypes, Says David Cotter, MD, PhD

 in Washington, DC, David Cotter, MD, PhD, an assistant clinical professor at the University of Nevada, presented the session, “Hair Loss Track: JAK-ing Up Alopecia Areata,” on Friday, June 27th. In an on-site interview with 

, Cotter discussed the rationale for targeting the JAK-STAT pathway in 

, as well as specific clinical or phenotypic patterns of this disease that appear to respond better or worse to JAK inhibition.

“What we see clinically is usually coin or circular-shaped areas of non-scarring alopecia that can transform and extend to be complete hair loss in the entire body, in things like alopecia universalis,” Cotter said. “Because of that, it makes a lot of sense to target the T cells to treat this disease, and when we think about some of the best T cell targeting medications that we have available to us, those are JAK inhibitors.”

Patients who respond the best to JAK inhibitors include those with limited disease. It is harder to treat alopecia universalis and totalis, although some medications work better for these alopecia types. An ophiasis pattern, which is a distribution of alopecia that runs from the temporal scalp down the occipital scalp, is even harder to treat.

“…but with Jak inhibitors, it really does even out the playing field,” Cotter said. “With these new medications, most people are able to get meaningful hair regrowth within a matter of time. When we think about what that matter of time is, though, it's never fast enough for anyone; we're talking about months, sometimes even out past a year, to get complete or clinically meaningful hair regrowth.”

When treating alopecia areata, Cotter always considers disease severity, comorbid diseases, and therapeutic options. For instance, for patients who have widespread scalp disease, he considers systemic therapy, such as baricitinib, ruxolitinib, and most recently, duruxalitib.

“We’ve got a wide array of medications to choose… that are currently FDA-approved on-label for the disease,” Cotter said. “[We are] looking at large network meta-analyses to ask the question: which drug is most effective at currently FDA-approved doses?”

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

At SDPA 2025, Cotter highlights clinical patterns in alopecia areata that may respond better, or worse, to JAK inhibition and shares his approach to systemic therapy.

David Cotter, MD, PhD

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