FDA SIDE EFFECTS UPDATE: Bactrim And The Risk Of Extreme Autoimmune Reaction, Plus More

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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 Bactrim, Isonazid, Ongentys, Paxlovid, and Prolensa.</p>
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<h2 class="wp-block-heading">How to Read This Report</h2>
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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" target="_blank" rel="noreferrer noopener">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">Bactrim and Bactrim DS (active ingredient: sulfamethoxazole; trimethoprim) tablets; Sulfamethoxazole and Trimethoprim tablets, injection, oral solution; Sulfatrim pediatric oral suspension (active ingredient: sulfamethoxazole; trimethoprim)</h3>
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<p><strong>Initial FDA Approva</strong>l: 1973</p>
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<p><strong>Side Effect Update Date</strong>: February 21, 2025</p>
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<p><strong>Medication Description</strong>: Used to treat bacterial infections, including pneumonia, urinary tract infections, and shigellosis, in adults and children aged two months and older.</p>
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<p><strong>Updated Side Effects/Safety Information</strong>: In the “Warnings and Precautions” and “Adverse Reactions” section, there is a new warning that cases of <a href="https://primaryimmune.org/understanding-primary-immunodeficiency/types-of-pi/hemophagocytic-lymphohistiocytosis-hlh" target="_blank" rel="noreferrer noopener">hemophagocytic lymphohistiocytosis (HLH)</a> have been reported in patients treated with sulfamethoxazole-trimethoprim. HLH is a life-threatening immune response with symptoms of extreme systemic inflammation. Signs and symptoms of HLH often include fever, liver or spleen enlargement, rash, and swollen lymph nodes. Additional symptoms may include neurologic symptoms, high ferritin levels, anemia, high triglycerides, and liver enzyme and coagulation abnormalities. Individuals are advised to discontinue the medication at the first sign of an adverse reaction.</p>
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<p><strong>Essential Extras</strong>: Sulfa drugs like Bactrim are common <a href="https://medlineplus.gov/ency/article/000819.htm" target="_blank" rel="noreferrer noopener">allergy-causing medications</a>.</p>
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<p><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=2458" target="_blank" rel="noreferrer noopener">Bactrim DS FDA Safety Label Change</a> and<a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/017377s085lbl.pdf" target="_blank" rel="noreferrer noopener"> Revised Drug Label</a> (Bactrim and Bactrim DS tablets) and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/018374s029lbl.pdf" target="_blank" rel="noreferrer noopener">Revised Drug Label</a> (Bactrim injection)</p>
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<p><a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=2539" target="_blank" rel="noreferrer noopener">Sulfamethoxazole and Trimethoprim FDA Safey Label Change</a> (tablets) and<a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/018598s056lbl.pdf" target="_blank" rel="noreferrer noopener"> Revised Drug Label</a> (tablets)</p>
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<p><a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=2540" target="_blank" rel="noreferrer noopener">Sulfatrim Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/018615s086lbl.pdf" target="_blank" rel="noreferrer noopener">Revised Drug Label</a></p>
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<h3 class="wp-block-heading">Isoniazid (active ingredient: isoniazid) tablets; Nydrazid (active ingredient: isoniazid) injection</h3>
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<p><strong>Initial FDA Approval</strong>: 1952 (isoniazid)</p>
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<p><strong>Side Effect Update Date</strong>: February 5, 2025</p>
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<p><strong>Medication Description</strong>: Used along with other medications to treat active cases of tuberculosis (TB). It is also used alone to prevent tuberculosis.</p>
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<p><strong>Updated Side Effects/Safety Information:</strong> The label was updated to include the risk of potentially life-threatening hypersensitivity reactions called <a href="https://www.aaaai.org/tools-for-the-public/allergy,-asthma-immunology-glossary/severe-cutaneous-adverse-reaction-(scar)-defined" target="_blank" rel="noreferrer noopener">Severe Cutaneous Adverse Reactions (SCARs)</a>. These include toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome (SJS), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP). Fever, rash, and blisters (with or without peeling skin) are common symptoms.</p>
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<p>Cases of <a href="https://www.uspharmacist.com/article/druginduced-neurologic-conditions" target="_blank" rel="noreferrer noopener">cerebellar syndrome</a> have also been reported, and this risk was added to the postmarketing experiences section. Most cases of cerebellar syndrome reported for isoniazid involve patients with chronic kidney disease (CKD). However, cerebellar syndrome was also reported in patients without CKD. Cerebellar syndrome symptoms may include abnormal gait or muscle movements in trunk and limbs, tremor, speech disorder, and involuntary eye movements.</p>
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<p><strong>FDA Safety Announcement:</strong> <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=304" target="_blank" rel="noreferrer noopener"> Isoniazid FDA Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/008678s030lbl.pdf" target="_blank" rel="noreferrer noopener">Revised Drug Label<br></a><a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=3080" target="_blank" rel="noreferrer noopener">Nydrazid FDA Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/008662s020lbl.pdf" target="_blank" rel="noreferrer noopener">Revised Drug Label</a></p>
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<h3 class="wp-block-heading">Ongentys (active ingredient: opicapone) tablets</h3>
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<p><strong>Initial FDA Approval</strong>: 2020</p>
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<p><strong>Side Effect Update Date</strong>: February 7, 2025</p>
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<p><strong>Medication Description</strong>: Treats Parkinson’s disease</p>
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<p><strong>Updated Side Effects/Safety Information</strong>: A new warning has been issued regarding the risk of falls and injuries among people using the drug. The adverse event of “falls” was added in the postmarketing experience section.</p>
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<p><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=3078" target="_blank" rel="noreferrer noopener">Ongentys FDA Safety Label Change</a> and<a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/212489s007lbl.pdf" target="_blank" rel="noreferrer noopener"> Revised Drug Label</a></p>
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<h3 class="wp-block-heading">Paxlovid (active ingredients: nirmatrelvir; ritonavir) copackaged pills</h3>
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<p><strong>Initial FDA Approval</strong>: 2023</p>
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<p><strong>Side Effect Update Date</strong>: February 12, 2025</p>
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<p><strong>Medication Description</strong>: Treats mild-to-moderate cases of COVID-19 in adults who are at high risk for progression to severe COVID-19.</p>
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<p><strong>Updated Side Effects/Safety Information</strong>: Provides clinical trial results for non-hospitalized patients with severe kidney disease. Lower, less frequent dose recommendations are provided for patients with moderate or severe kidney disease, as kidney impairment may increase nirmatrelvir exposure and lead to Paxlovid adverse reactions. Dialysis patients are advised to take their doses after undergoing dialysis.</p>
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<p>Additionally, the prostate cancer medication enzalutamide (brand name Xtandi) has been added to the list of contraindicated drugs. Paxlovid should not be used even after immediately stopping enzalutamide. Also, dosage instructions for all patients were modified to clarify that doses should be taken at about the same time each day.</p>
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<p><strong>Essential Extras</strong>: More drug interactions are on the <a href="https://paxlovid.pfizerpro.com/drug-interactions" target="_blank" rel="noreferrer noopener">Paxlovid website</a> and on the drug label.</p>
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<p><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=3049" target="_blank" rel="noreferrer noopener"> FDA Paxlovid Safety Label Change</a> and<a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/217188s010lbl.pdf" target="_blank" rel="noreferrer noopener"> Revised Drug Label</a></p>
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<h3 class="wp-block-heading">Prolensa (active ingredient; bromfenac sodium) eye drop solution</h3>
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<p><strong>Initial FDA Approval:</strong> 1997</p>
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<p><strong>Side Effect Update Date</strong>: February 18, 2025</p>
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<p><strong>Medication Description:</strong> A nonsteroidal anti-inflammatory (NSAID) topical solution that treats post-operative inflammation and eye pain in patients who have undergone cataract surgery.</p>
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<p><strong>Updated Side Effects/Safety Information</strong>: A new warning advises about the risk of medication contamination and instructs patients not to touch the dropper tip to the eye, eyelids, or any surface. It also emphasizes the importance of replacing the bottle cap after each use.</p>
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<p><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=3083" target="_blank" rel="noreferrer noopener">Prolensa FDA Safety Label Change</a> and<a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/203168s005lbl.pdf" target="_blank" rel="noreferrer noopener"> Revised Label</a></p>
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