FDA SIDE EFFECTS UPDATE: Risk of Serotonin Syndrome With Antibiotic, Severe Bleeding with Blood Thinner

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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 Cleocin (clindamycin hydrochloride), Sivextro (tedizolid phosphate), Xarelto (rivaroxaban), and Xeljanz (tofacitinib).</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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<h3 class="wp-block-heading">Cleocin Hydrochloride (clindamycin hydrochloride) capsules and Cleocin Phosphate (clindamycin phosphate) solution for intravenous use or injection</h3>
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<p><strong>Initial FDA Approval</strong>: 1970<br><strong>Side Effect Update Date</strong>: March 26, 2026<br><strong>Medication Description</strong>: Antibiotic for serious bacterial infections<br><strong>Updated Side Effects/Safety Information</strong>: A new warning states that acute myocardial ischemia (reduced blood flow to the heart) may occur as part of an allergic reaction, with or without myocardial infarction (heart attack).<br><br><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=279">Cleocin Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/050162s107lbl.pdf">Revised Label</a> and <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=97">Cleocin Phosphate Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/050441s091lbl.pdf">Revised Label</a></p>
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<h3 class="wp-block-heading">Sivextro (tedizolid phosphate) tablets or injection (for intravenous use)</h3>
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<p><strong>Initial FDA Approval</strong>: 2014<br><strong>Side Effect Update Date:</strong> February 27, 2026<br><strong>Medication Description</strong>: Antibiotic for serious bacterial skin infections<br><strong>Updated Side Effects/Safety Information</strong>: A new warning about the risk of <a href="https://medlineplus.gov/ency/article/007272.htm">serotonin syndrome,</a> a potentially life-threatening reaction that can happen when Sivextro is taken with certain other medicines, including some antidepressants, opioid pain medicines, anxiety medicines, and some migraine drugs. Symptoms of serotonin syndrome include fever, sweating, agitation, unusual eye movements, difficulty with coordination, stiff muscles, and twitching. </p>
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<p>Additionally, a new warning was added about Clostridioides difficile-associated diarrhea. Patient information was updated to specify that Sivextro TABLETS should not be used by children weighing less than 77 pounds.</p>
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<p><strong>Essential Extras</strong>: Linezolid (Zyvox brand name, approved in 2000) is an<a href="https://www.britannica.com/science/oxazolidinone"> oxazolidinone</a> type of antibiotic like Sivextro. In 2011, the FDA issued a safety communication about the rare side effect of serotonin syndrome and updated the <a href="https://www.dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=9d1b4d0a-0fd9-448b-a28f-51ed05a5a0cf">linezolid label</a>. <br><br><strong>FDA Safety Announcement:</strong> <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=509">Sivextro Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/205435s019lbl.pdf">Revised Label</a></p>
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<h3 class="wp-block-heading">Xarelto (rivaroxaban) tablets and oral solution</h3>
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<p><strong>Initial FDA Approval</strong>: 2011<br><strong>Side Effect Update Date</strong>: March 24, 2026<br><strong>Medication Description</strong>: Blood thinner used to help prevent and treat blood clots and to reduce the risk of stroke and other clot-related complications<br><strong>Updated Side Effects/Safety Information</strong>: A new warning states that no specific antidote is available to reverse Xarelto’s anti–factor Xa activity — the way it inhibits a key clotting factor in the blood. This may be especially important in cases of severe bleeding or emergency surgery. Andexxa (coagulation factor Xa (recombinant), inactivated-zhzo) was previously used as an antidote but was <a href="https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/update-safety-andexxa">recently withdrawn</a> from the U.S. market for safety reasons.<br><br><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=2729">Xarelto Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/215859s007lbl.pdf">Revised Label</a></p>
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<h3 class="wp-block-heading">Xeljanz (tofacitinib) and Xeljanz XR (extended-release) tablets and oral solution</h3>
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<p><strong>Initial FDA Approval</strong>: 2012<br><strong>Side Effect Update Date</strong>: March 6, 2026<br><strong>Medication Descriptio</strong>n: Used to treat several autoimmune conditions, including rheumatoid arthritis (RA), psoriatic arthritis, ankylosing spondylitis, polyarticular-course juvenile idiopathic arthritis, and ulcerative colitis.<br><strong>Updated Side Effects/Safety Information</strong>: Warnings about serious infections have been strengthened, adding bronchitis, septic shock, gastroenteritis, and sepsis to the list of reported infections. The label also now includes safety data showing a higher risk of fractures in adults with rheumatoid arthritis who took higher doses of Xeljanz versus a TNF (<a href="https://rheumatology.org/patients/tumor-necrosis-factor-tnf-inhibitors">Tumor Necrosis Factor</a>) inhibitor. Because of these added risks, the higher-dose daily regimen (10 mg twice daily of Xeljanz or 22 mg once daily of Xeljanz XR) is not recommended for rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, or polyarticular-course juvenile idiopathic arthritis.<br><br><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=1236">FDA Xeljanz and Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/213082s013lbl.pdf">Revised Label</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/2026/208246s027lbl.pdf">Revised Label</a></p>
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