FDA SIDE EFFECTS UPDATE: Low Blood Sugar Warning for Xeljanz, Rinvoq, and other JAK Inhibitors

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<p>Welcome to the FDA Side Effects Update. This series is designed to keep you informed about the latest safety advisories and newly documented side effects of your medications. In this installment, we’re highlighting safety updates concerning eight Janus kinase (JAK) inhibitor medications that treat autoimmune diseaes like rheumatoid arthritis, ulcerative colitis, and various skin conditions: Anzupgo, Leqselvi, Litfulo, Olumiant, Opzelura, Rinvoq, Sotyktu, and Xeljanz. We’re also including an update for the iron replacement medicine Feraheme. </p>
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<p>This report is prepared using the most recent information posted in the<a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm"> SrLC database</a>. It highlights recent safety labeling changes. It includes only newly reported side effects and safety information; additional side effects and warnings will appear on the drug label. Not all recent changes to the SrLC database or the label may be listed here. For all changes and the complete list of warnings and side effects, please click on the drug label link.</p>
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<p>Each of the items (approval and update dates, drug names, etc.) contained in this report are obtained from the SrLC. The side effects and medication descriptions are simplified and made clearer, if needed. Sometimes, additional sources, like a medical dictionary, may be used to translate technical medical phrases. Other sources (company news, FDA press releases, etc.) may be used to learn about some label changes.</p>
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<h2 class="wp-block-heading">Updated Side Effect Warnings for JAK Inhibitor Medications</h2>
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<p>Janus kinase (JAK) enzymes are types of proteins that help regulate the body’s immune defense and blood cell development. When JAK enzymes are not regulating properly, the body may have too much inflammation, resulting in autoimmune conditions affecting the joints, connective tissues, blood, digestive organs, or skin. </p>
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<p>A <a href="https://www.cancer.gov/publications/dictionaries/cancer-terms/def/janus-kinase-inhibitor">Janus kinase (JAK) inhibitor</a> is a type of medication that blocks some of the effects of JAK proteins, reducing the body’s immune response. Like other <a href="https://medshadow.org/conditions-treatments/autoimmune-conditions/diet-exercise-and-drugs-for-autoimmune-diseases/">DMARDs</a> (Disease Modifying Antirheumatic Drugs), the medications can make patients more susceptible to infections. JAK inhibitor medications may also increase the risk of <a href="https://www.fda.gov/safety/medical-product-safety-information/janus-kinase-jak-inhibitors-drug-safety-communication-fda-requires-warnings-about-increased-risk">heart attacks, blood clots, and certain cancers</a>.</p>
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<p>In March 2026, the FDA sent notifications (such as this one <a href="https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2026/211675Orig1s034,218347Orig1s008ltr.pdf">referenced in a letter to </a>AbbVie) informing sponsors to update drug labels with safety information about the risk of low blood sugar (hypoglycemia) in diabetes patients taking JAK inhibitor medications. This risk was first flagged as a potential safety concern in the<a href="https://www.fda.gov/drugs/fda-adverse-event-monitoring-system-aems/april-june-2024-new-safety-information-or-potential-signals-serious-risks-identified-fda-adverse"> June 2024 New Safety Information or Potential Signals of Serious Risks from FDA Adverse Event Reports</a>. This side effect update does not apply to JAK inhibitors used to treat blood disorders, including Jakafi (ruxolitinib) or Inrebic (fedratinib).</p>
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<h3 class="wp-block-heading">Anzupgo (delgocitinib) topical cream</h3>
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<p><strong>Initial FDA Approval</strong>: 2025<br><strong>Side Effect Update Date</strong>: June 30, 2026<br><strong>Medication Description</strong>: A prescription cream for adults with chronic moderate to severe hand eczema.<br><strong>Updated Side Effects/Safety Information</strong>: Updated safety information warns that it is not known whether Anzupgo carries the same risks as oral JAK inhibitors. Oral JAK inhibitors have been associated with hypoglycemia, or low blood sugar, in patients with diabetes.<br><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=3300">FDA Anzupgo Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/219155s004lbl.pdf">Revised Label</a><br>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more<br></p>
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<h3 class="wp-block-heading">Leqselvi (deuruxolitinib) tablets</h3>
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<p><strong>Initial FDA Approval</strong>: 2023<br><strong>Side Effect Update Date:</strong> June 30, 2026<br><strong>Medication Description</strong>: A Janus kinase (JAK) inhibitor that treats adults with severe <a href="https://dermnetnz.org/topics/alopecia-areata">alopecia areata</a>, an autoimmune condition causing hair loss.<br><strong>Updated Side Effects/Safety Information</strong>: Updated safety information warns about the risk of severe hypoglycemia (low blood sugar) in patients with diabetes. Healthcare providers should monitor blood glucose closely during treatment, and patients should report symptoms of hypoglycemia such as shaking, sweating, nervousness, dizziness, irritability, or confusion.<br><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=3299">FDA Leqselvi Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/217900s002lbl.pdf">Revised Label<br></a>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more</p>
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<h3 class="wp-block-heading">Litfulo (ritlecitinib tosylate) capsules</h3>
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<p><strong>Initial FDA Approval</strong>: 2023<br><strong>Side Effect Update Date</strong>: June 30, 2026<br><strong>Medication Description</strong>: A Janus kinase (JAK) inhibitor that treats adults and adolescents with severe <a href="https://dermnetnz.org/topics/alopecia-areata">alopecia areata</a>, an autoimmune condition causing hair loss.<br><strong>Updated Side Effects/Safety Information</strong>: Updated safety information warns about the risk of severe hypoglycemia (low blood sugar) in patients with diabetes. Healthcare providers should monitor blood glucose closely during treatment, and patients should report symptoms of hypoglycemia such as shaking, sweating, nervousness, dizziness, irritability, or confusion.<br><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=3301">FDA Litfulo Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/215830s001lbl.pdf">Revised Label</a><br>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more</p>
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<h3 class="wp-block-heading">Olumiant (Baricitinib) tablets</h3>
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<p><strong>Initial FDA Approval</strong>: 2018<br><strong>Side Effect Update Date</strong>: June 30, 2026<br><strong>Medication Description</strong>: A Janus kinase (JAK) inhibitor that treats rheumatoid arthritis. JAK inhibitors help relieve symptoms of autoimmune conditions by decreasing the activity of the immune system. Because of the risk of serious side effects, Olumiant is only to be used by those who have had an inadequate response to a <a href="https://rheumatology.org/patients/tumor-necrosis-factor-tnf-inhibitors">Tumor Necrosis Factor blocker</a>.<br><strong>Updated Side Effects/Safety Information</strong>: Updated safety information warns about the risk of severe hypoglycemia (low blood sugar) in patients with diabetes. Healthcare providers should monitor blood glucose closely during treatment, and patients should report symptoms of hypoglycemia such as shaking, sweating, nervousness, dizziness, irritability, or confusion.<br><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=2084">FDA Olumiant Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/207924s011lbl.pdf">Revised Label</a><br>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more </p>
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<h3 class="wp-block-heading">Opzelura (ruxolitinib) cream, for topical use</h3>
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<p><strong>Initial FDA Approval</strong>: 2011<br><strong>Side Effect Update Date</strong>: June 30, 2026<br><strong>Medication Description</strong>: A topical treatment for mild or moderate eczema in non-immunocompromised patients 2 years of age and older; also treats <a href="https://medlineplus.gov/vitiligo.html">vitiligo</a> in patients 12 years of age and older. Vitiligo causes white patches on the skin.<br><strong>Updated Side Effects/Safety Information</strong>: Updated safety information warns that it is not known whether using Anzupgo has the same risks as taking oral JAK inhibitors. The update warns that orally taken JAK inhibitors have been associated with hypoglycemia (low blood sugar) in patients with diabetes. There is an additional warning that orally taken JAK inhibitors have been associated with increased cholesterol levels.<br><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=2648">FDA Opzelura Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/215309s009sdn953lbl.pdf">Revised Label</a><br>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more</p>
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<h3 class="wp-block-heading">Rinvoq (active ingredient: upadacitinib) extended-release tablets and Rinvoq LQ oral solution</h3>
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<p><strong>Initial FDA Approval</strong>: 2019<br><strong>Side Effect Update Date</strong>: June 30, 2026<br><strong>Medication Description</strong>: A Janus kinase (JAK) inhibitor that treats rheumatoid arthritis, ulcerative colitis, eczema, and giant cell arteritis (GCA) in adults. JAK inhibitors help relieve symptoms of autoimmune conditions by decreasing immune system activity. Because of the risk of serious side effects, Rinvoq is only to be used by patients who have had an inadequate response to a <a href="https://rheumatology.org/patients/tumor-necrosis-factor-tnf-inhibitors">tumor necrosis factor (TNF) blocker</a>.<br><strong>Updated Side Effects/Safety Information</strong>: Updated safety information warns about the risk of severe hypoglycemia (low blood sugar) in patients with diabetes. Healthcare providers should monitor blood glucose closely during treatment, and patients should report symptoms of hypoglycemia such as shaking, sweating, nervousness, dizziness, irritability, or confusion.<br><strong>FDA Safety Announcement</strong>:<a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=2285"> FDA Rinvoq Safety Label Change</a>,<a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=3096"> FDA Rinvoq Liquid Safety Label Change</a>, and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/218347Orig1s008,211675Orig1s034lbl.pdf">Revised Label</a> (shared label)<br>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more</p>
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<h3 class="wp-block-heading">Sotyktu (deucravacitinib) tablets</h3>
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<p><strong>Initial FDA Approval</strong>: 2022<br><strong>Side Effect Update Date</strong>: June 30, 2026<br><strong>Medication Description</strong>: Treats adults with moderate-to-severe plaque psoriasis or psoriatic arthritis. Sotyktu is a <a href="https://www.ncbi.nlm.nih.gov/books/NBK563322/">tyrosine kinase 2 </a>(TYK2) inhibitor and blocks enzymes in the same family as those targeted by JAK inhibitor medications.<br><strong>Updated Side Effects/Safety Information</strong>: Updated safety information warns that it is not known whether TYK2 inhibition may be associated with the observed or potential adverse reactions of JAK inhibition. There is a warning that orally taken JAK inhibitors have been associated with hypoglycemia (low blood sugar) in patients with diabetes. Diabetic patients should notify their healthcare provider if they develop signs or symptoms of hypoglycemia such as shaking, sweating, nervousness, dizziness, irritability, or confusion.<br><strong>FDA Safety Announcement</strong>:<a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=3259"> FDA Sotyktu Safety Label Change</a>, and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/214958s006sdn685lbl.pdf">Revised Label</a><br>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more</p>
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<h3 class="wp-block-heading">Xeljanz (tofacitinib) and Xeljanz XR (extended-release) tablets and Xeljanz oral solution</h3>
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<p><strong>Initial FDA Approval</strong>: 2012<br><strong>Side Effect Update Date</strong>: June 30, 2026<br><strong>Medication Description</strong>: A Janus kinase (JAK) inhibitor that treats certain autoimmune conditions, including: rheumatoid arthritis (RA), psoriatic arthritis, ankylosing spondylitis, polyarticular-course juvenile idiopathic arthritis, and ulcerative colitis. JAK inhibitors help relieve symptoms of autoimmune conditions by decreasing immune system activity. Because of the risk of serious side effects, Xeljanz is only to be used by those who have had an inadequate response to a <a href="https://rheumatology.org/patients/tumor-necrosis-factor-tnf-inhibitors">Tumor Necrosis Factor inhibitor</a>.<br><strong>Updated Side Effects/Safety Information</strong>: Updated safety information warns about the risk of severe hypoglycemia (low blood sugar) in patients with diabetes. Healthcare providers should monitor blood glucose closely during treatment, and patients should report symptoms of hypoglycemia such as shaking, sweating, nervousness, dizziness, irritability, or confusion.<br><strong>FDA Safety Announcemen</strong>t: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=1236">FDA Xeljanz Safety Label Change</a>, <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=2562">FDA Xeljanz Oral Solution Safety Label Change</a>; <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=1237">FDA Xeljanz XR Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/203214s043,213082s016,208246s029lbl.pdf">Revised Label</a> (shared label)<br>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more</p>
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<h2 class="wp-block-heading">Updated Side Effect Warning for Iron Replacement Treatment</h2>
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<h3 class="wp-block-heading">Feraheme (ferumoxytol) injection</h3>
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<p><strong>Initial FDA Approval</strong>: 2009<br><strong>Side Effect Update Date</strong>: May 27, 2026<br><strong>Medication Description</strong>: Treats iron deficiency anemia in adults when oral iron is ineffective or cannot be used. Given by IV infusion in two doses, 3 to 8 days apart.<br><strong>Updated Side Effects/Safety Information</strong>: Updated safety information warns that Feraheme has caused irritation and long-lasting brown discoloration or staining of skin if medicine leaks out (“<a href="https://my.clevelandclinic.org/health/articles/24925-extravasation">extravasation</a>”) at the infusion site. The Patient Medication Guide warns that because Feraheme may interfere with MRI test results for up to three months after the last dose, planned MRIs should be done before starting treatment with Feraheme. The Patient Medication Guide also adds low blood pressure to the list of common side effects.<br><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=1445">Feraheme FDA Safety Label Change</a> and<a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/022180s026lbl.pdf"> Revised Drug Label<br></a>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.</p>
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