75/100 · Elevated
Manufactured by Bausch Health US, LLC
Acyclovir Adverse Events: High Serious Reaction Rate
186,079 FDA adverse event reports analyzed
Last updated: 2026-05-12
ACYCLOVIR is a medication tracked in the FDA Adverse Event Reporting System (FAERS), manufactured by Bausch Health US, LLC. Based on analysis of 186,079 FDA adverse event reports, ACYCLOVIR has a safety score of 75 out of 100. This score indicates a relatively favorable safety profile, with fewer or less severe adverse events compared to many other tracked medications. The most commonly reported adverse reactions for ACYCLOVIR include FATIGUE, DIARRHOEA, OFF LABEL USE, PNEUMONIA, NAUSEA. This page provides a comprehensive breakdown of reported side effects, safety signals, patient demographics, and AI-powered safety analysis for ACYCLOVIR.
Acyclovir has a safety concern score of 75 out of 100, placing it in the elevated concern category based on analysis of FDA adverse event data. The FDA has received approximately 186,079 adverse event reports for this medication, which is primarily manufactured by Bausch Health Us, Llc.
The most commonly reported adverse events include Fatigue, Diarrhoea, Off Label Use. Of classified reports, 72.4% were designated as serious by the FDA, meaning they involved hospitalization, disability, or other significant medical outcomes. Acyclovir reports include a high percentage of serious adverse events, particularly respiratory and gastrointestinal issues.
The most common reactions are fatigue, diarrhea, and pneumonia, indicating a broad range of potential side effects. Reports show a significant number of serious outcomes, with death being one of the top reported reactions.
Patients taking Acyclovir should monitor for the commonly reported side effects and contact their healthcare provider if they experience any unusual symptoms. Acyclovir can interact with other drugs, and warnings include potential for severe respiratory and gastrointestinal issues. This analysis is based on voluntary FDA adverse event reports and should not replace professional medical advice.
Acyclovir received a safety concern score of 75/100 (elevated concern). This is based on a 72.4% serious event ratio across 109,610 classified reports. The score accounts for 186,079 total adverse event reports and 100 distinct reaction types. This elevated score indicates a notable proportion of serious adverse events and warrants careful monitoring.
Adverse event reports by sex: Female: 51,333, Male: 51,024, Unknown: 286. The most frequently reported age groups are age 72 (2,236 reports), age 68 (2,221 reports), age 70 (2,203 reports). These demographics reflect reporting patterns and may not represent the full patient population.
Out of 109,610 classified reports for ACYCLOVIR:
The FDA classifies an adverse event as “serious” if it results in death, hospitalization, disability, congenital anomaly, or requires intervention to prevent permanent damage.
Demographics reflect voluntary FDA adverse event reporting patterns and may not represent the full patient population.
Acyclovir can interact with other drugs, and warnings include potential for severe respiratory and gastrointestinal issues.
If you are taking Acyclovir, here are important things to know. The most commonly reported side effects include fatigue, diarrhoea, off label use, pneumonia, nausea. While many of these may be mild and temporary, you should contact your healthcare provider if any symptoms are severe or persistent. Monitor for signs of severe respiratory or gastrointestinal issues, especially in elderly patients. Be aware of potential drug interactions, particularly with immunosuppressants and antivirals. If you experience a serious adverse reaction, seek emergency medical attention immediately or call 911. You can report side effects to the FDA's MedWatch program at 1-800-FDA-1088.
Regulatory oversight is ongoing, with a focus on monitoring serious adverse events and drug interactions.
The FDA has received approximately 186,079 adverse event reports associated with Acyclovir. These reports come from healthcare professionals, consumers, and manufacturers through the FDA Adverse Event Reporting System (FAERS). Note that the number of reports does not directly indicate the frequency of side effects, as adverse events are voluntarily reported and may be underrepresented.
The most frequently reported adverse events for Acyclovir include Fatigue, Diarrhoea, Off Label Use, Pneumonia, Nausea. By volume, the top reported reactions are: Fatigue (7,611 reports), Diarrhoea (7,062 reports), Off Label Use (5,797 reports). These figures reflect FDA adverse event reports and may not represent the true incidence rate of these side effects in all patients taking Acyclovir.
Out of 109,610 classified reports, 79,396 (72.4%) were classified as serious and 30,214 as non-serious. The FDA classifies an event as "serious" if it results in death, hospitalization, disability, or other medically significant outcomes. A higher serious-event ratio warrants closer attention but does not necessarily mean the drug is unsafe.
Adverse event reports for Acyclovir break down by patient sex as follows: Female: 51,333, Male: 51,024, Unknown: 286. This distribution reflects reporting patterns rather than actual risk differences between groups. Reporting rates can be influenced by prescribing patterns, disease demographics, and reporting behavior.
The most frequently reported age groups for Acyclovir adverse events are: age 72: 2,236 reports, age 68: 2,221 reports, age 70: 2,203 reports, age 69: 2,172 reports, age 67: 2,144 reports. Age-related reporting patterns can reflect both the demographics of the patient population and potential age-related susceptibility to certain side effects.
The primary manufacturer associated with Acyclovir adverse event reports is Bausch Health Us, Llc. Multiple manufacturers may produce generic versions of this drug. The manufacturer listed reflects the most frequently reported brand in FDA adverse event data.
Beyond the most common reactions, other reported adverse events for Acyclovir include: Pyrexia, Death, Drug Ineffective, Rash, Dyspnoea. Less common side effects can still be clinically significant. Patients should report any unusual symptoms to their healthcare provider.
You can report adverse events from Acyclovir to the FDA through their MedWatch program at www.fda.gov/medwatch, by calling 1-800-FDA-1088, or by completing Form FDA 3500. Healthcare professionals, consumers, and manufacturers can all submit reports. Reporting helps the FDA monitor drug safety after approval.
Acyclovir has a safety concern score of 75 out of 100 (elevated concern). This score is calculated from the ratio of serious to non-serious adverse events, the diversity of reported reactions, and the overall volume of reports relative to usage. Acyclovir reports include a high percentage of serious adverse events, particularly respiratory and gastrointestinal issues.
Key safety signals identified in Acyclovir's adverse event data include: High percentage of serious reactions (72.4%). Common reactions include fatigue, diarrhea, and pneumonia. Death is one of the top reported reactions. These signals are derived from patterns in FDA reports and should be discussed with a healthcare provider for personalized assessment.
Acyclovir can interact with other drugs, and warnings include potential for severe respiratory and gastrointestinal issues. Always inform your healthcare provider about all medications, supplements, and over-the-counter drugs you are taking before starting Acyclovir.
Monitor for signs of severe respiratory or gastrointestinal issues, especially in elderly patients. Be aware of potential drug interactions, particularly with immunosuppressants and antivirals.
Acyclovir has 186,079 adverse event reports on file with the FDA. The most common reactions are fatigue, diarrhea, and pneumonia, indicating a broad range of potential side effects. The volume of reports for Acyclovir reflects both the drug's usage level and the vigilance of the reporting community.
Regulatory oversight is ongoing, with a focus on monitoring serious adverse events and drug interactions. For the most current regulatory information, check the FDA's drug labeling database or consult your pharmacist.
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