Paxlovid side effects
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Common Side Effects of Paxlovid (Nirmatrelvir/Ritonavir)
Paxlovid, a combination of nirmatrelvir and ritonavir, is widely used to treat COVID-19. The most frequently reported side effects include changes in taste (dysgeusia), loss of taste (ageusia), headache, and loss of smell (anosmia). These neurological symptoms are more common in patients taking Paxlovid compared to other COVID-19 treatments, and clinicians are advised to monitor especially female patients for these effects within the first 30 days of treatment . Diarrhea is also commonly reported, particularly among pregnant women treated with Paxlovid .
Neurological and Sensory Adverse Reactions
Paxlovid is associated with a higher rate of neurological side effects than other COVID-19 medications. These include dysgeusia, ageusia, headache, and anosmia. Headache and anosmia are not rare and should be expected as possible side effects .
Hyponatremia and SIADH
There have been reports of severe hyponatremia (low sodium levels) in patients taking Paxlovid, sometimes requiring intensive care. Symptoms such as weakness, nausea, and dehydration were observed in these cases. The mechanism is not fully understood, but one case suggested that Paxlovid may induce SIADH (syndrome of inappropriate antidiuretic hormone secretion), leading to severe hyponatremia 23.
Drug-Drug Interactions and Related Toxicities
Paxlovid can interact with many other medications due to its effect on liver enzymes (CYP3A4) and drug transport proteins (P-gp). These interactions can increase the risk of toxicities from other drugs, such as anticoagulants, calcium channel blockers, statins, immunosuppressants, antiarrhythmics, and antipsychotics. Careful review of a patient’s medications and close monitoring are necessary to avoid serious adverse effects 567.
Safety in Special Populations
In pregnant women, Paxlovid was generally well tolerated, with no severe adverse events reported. The most common side effects were dysgeusia and diarrhea. However, a higher rate of caesarean deliveries was observed in the Paxlovid group, and more newborns were small for gestational age, though this was not statistically significant. Long-term follow-up is recommended for these patients . In elderly patients, including centenarians with renal insufficiency, Paxlovid was used without significant side effects such as liver or kidney dysfunction, diarrhea, nausea, or vomiting .
Serious and Long-Term Side Effects
While most studies report that Paxlovid is generally safe, some research suggests the need for long-term monitoring. One study found that Paxlovid may accelerate cartilage degeneration and increase the risk of osteoarthritis in animal models, possibly due to increased cellular stress and oxidative damage. This potential long-term risk requires further investigation in humans .
Overall Safety Profile
Meta-analyses and rapid reviews indicate that Paxlovid does not significantly increase the risk of serious adverse events compared to other treatments or placebo. However, patients should be monitored for renal and liver function, as well as for possible drug interactions 79.
Conclusion
Paxlovid is effective for treating COVID-19 and is generally well tolerated. The most common side effects are changes in taste, headache, diarrhea, and, less commonly, severe hyponatremia. Drug-drug interactions are a significant concern and require careful management. Long-term effects, such as potential cartilage degeneration, are still being studied. Regular monitoring and individualized patient assessment are essential to ensure safe use of Paxlovid.
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