Janus kinase (JAK) inhibitors are a relatively new type of treatment for moderate to severe plaque psoriasis and psoriatic arthritis (PsA). These medications work on specific parts of the immune system to help relieve symptoms. You and your doctor may consider this option if your current treatments don’t provide enough relief.

Like any medical treatment, JAK inhibitors come with the risk of side effects, though most are minor. It’s helpful to be informed about the symptoms so you can recognize these side effects if they do occur. Your health care provider will always weigh the pros and cons of a medication before determining the best treatment option for you.

Read on to learn more about some of the benefits and side effects of using JAK inhibitors for psoriasis and psoriatic arthritis.

5 Benefits of JAK Inhibitors

Following are five advantages of JAK inhibitors.

1. JAK Inhibitors Work in a Specific Way

JAK inhibitors are considered one of the more specific medicines you can take for psoriasis or psoriatic arthritis because they target individual parts of the immune system. Scientists believe psoriasis and PsA are caused in part by the activity of immune system messengers called cytokines. Some cytokines travel to immune cells and signal an inflammatory, or inflammation-causing, pathway that is thought to contribute to symptoms of psoriasis and PsA.

JAK enzymes, a type of molecule that live below the surface of your cells, play a role in the inflammatory process by acting in response to cytokines. JAK inhibitors aim to inhibit the function of JAK enzymes and interrupt the inflammatory process.

2. The FDA Approved Several JAK Inhibitors for Psoriasis and Psoriatic Arthritis

In clinical trials, the U.S. Food and Drug Administration (FDA) has studied the effectiveness of JAK inhibitors for people with a range of autoimmune conditions, including rheumatoid arthritis, spondylitis, ulcerative colitis, and other inflammatory diseases. These medications have been on the market to treat autoimmune diseases since 2012 and were recently approved for skin diseases such as atopic dermatitis (the most common subtype of eczema), alopecia areata, and psoriasis.

Three JAK inhibitors are FDA-approved for psoriasis and psoriatic arthritis as of 2023:

• Sotyktu (a formulation of deucravacitinib) — For psoriasis
• Xeljanz (a formulation of tofacitinib) — For PsA
• Rinvoq (a formulation of upadacitinib) — For PsA

Additional JAK inhibitors must go through randomized controlled trials before the FDA can approve them.

More than 50 people on MyPsoriasisTeam report taking JAK inhibitors, and this treatment type prompts conversations among members. One asked, “Has anyone tried Sotyktu yet? Recently approved by the FDA. It’s a once-daily pill.”

3. JAK Inhibitors Work Systemically

JAK inhibitors for psoriasis and PsA are systemic treatments — similar to biologics — since they work on your body as a whole. In contrast, topical medications like creams and ointments are local treatments, which work only on the area of skin where they are applied.

JAK inhibitors may be a good alternative if topical medications or biologics haven’t helped your moderate to severe psoriasis or if disease modifying antirheumatic drugs (DMARDs) haven’t helped your PsA. They act directly on the offending cells beneath the surface of your skin.

4. JAK Inhibitors May Be Taken by Mouth

The only JAK inhibitors approved for psoriasis or PsA are oral medications. Researchers are also studying the effectiveness of topical JAK inhibitors — that is, JAK inhibitor treatments that you apply directly to your skin. Oral JAK inhibitors can be taken twice or even just once a day.

Compared with topical psoriasis treatments that may require multiple applications throughout the day, oral JAK inhibitors may be more convenient and easier to add to your daily routine. They also often cost less than biologics.

5. JAK Inhibitors Are Highly Effective

Several studies have compared JAK inhibitors to a placebo (an inactive substance). One meta-analysis, which looked at the results of 15 studies, found that people who took tofacitinib tolerated the medication well — they had a low risk of adverse events (side effects). The participants also had a significant reduction in their psoriasis symptoms compared with the people in the placebo group.

One MyPsoriasisTeam member wrote about their positive experience in switching from a biologic medication to a JAK inhibitor: “There has been no lapse in effectiveness for over two years now.”

After treatment with a JAK inhibitor, people have seen decreases in discoloration, itching, and skin thickness associated with plaque psoriasis. People with PsA saw improvements in both skin discoloration and joint pain.

Overall, JAK inhibitors may be particularly helpful for people with both moderate to severe psoriasis and PsA.

6 Common Side Effects of Using JAK Inhibitors

Like all medicines, JAK inhibitors carry the risk of side effects. If your dermatology provider has prescribed a JAK inhibitor for you, it’s because they believe that the benefits outweigh your personal risk factors. Here are six of the more common side effects and symptoms to watch out for.

1. Nausea and Diarrhea

The nausea, diarrhea, and indigestion associated with JAK inhibitors often go away with use over time. If these symptoms persist, talk to your doctor to rule out other causes.

2. Dizziness

JAK inhibitors can cause dizziness, lightheadedness, and headaches. If you feel dizzy, lie down, rest, and then get up slowly. Drink plenty of fluids, and be sure to tell your doctor about this symptom.

3. Blood Pressure Changes

Taking a JAK inhibitor can raise your systolic blood pressure (the first number). Reach out to your doctor if you feel lightheaded or dizzy, which could indicate changes to your blood pressure.

4. Infections

Although JAK inhibition may help symptoms of psoriasis and psoriatic arthritis, it can also make it more difficult for the immune system to fight off other infections. Taking a JAK inhibitor can make you more likely to get certain infections and may increase their severity.

While on a JAK inhibitor, you may become more susceptible to infections such as the following.

Herpes Zoster

People taking tofacitinib reported developing herpes zoster (shingles), which causes a painful rash and blisters on one side of the face or body. The shingles rash resembles that of chickenpox — both illnesses are caused by the varicella-zoster virus.

Fungal Infections

Using JAK inhibitors increases the risk of serious infections, including fungal infections, which may cause symptoms such as fever, cough, or difficulty breathing.

Bacterial Infections

Bacterial infections associated with JAK inhibitors include urinary tract infections, which cause pain or burning with urination. There is also an increased risk of tuberculosis, especially in people who have had a known exposure to this potentially serious condition affecting the lungs.

Be sure to discuss your personal infection risks with your doctor. You should also keep your vaccinations current to decrease your risk of common infections. Your health care provider can advise you on which vaccinations you need and when you should get them.

5. Upper Respiratory Symptoms

Studies have found that people taking a JAK inhibitor are more likely to catch upper respiratory tract infections, such as the common cold. You might also get more severe symptoms like a cough and fever.

6. Weight Gain

Weight gain can occur when taking a JAK inhibitor, particularly upadacitinib. If you are suddenly putting on pounds, talk with your doctor to ensure there is no other cause for your unexpected weight change.

Talk to Others Who Understand

MyPsoriasisTeam is the social network for people with psoriasis and psoriatic arthritis and their loved ones. On MyPsoriasisTeam, more than 117,000 members come together to ask questions, give advice, and share their stories with others who understand life with psoriasis.

Have you taken a JAK inhibitor for psoriasis or PsA? Did you experience any side effects of these medications? Share your experience in the comments below, or start a conversation by posting on your Activities page.