Side Effects of Zovirax (acyclovir)

Zovirax (acyclovir) is an antiviral drug that interferes with the replication of herpes viruses such as herpes simplex 1 and 2, varicella-zoster, and Epstein-Barr virus.

• phenytoin,
• valproic acid,
• probenecid,
• theophylline,
• cidofovir,
• and amphotericin B or other drugs that reduce kidney function.

No studies have been conducted on the use of Zovirax in pregnant women. A registry study showed a similar rate of birth defects in women who used Zovirax during the first trimester compared to the general population. Zovirax is excreted in breast milk, and caution should be exercised when breastfeeding.

What are the side effects of Zovirax?

What are the common side effects of Zovirax?

The most common side effects are:

What are the serious side effects of Zovirax?

Other reported serious side effects include:

• agitation,
• confusion,
• rash,
• anemia,
• muscle pain,
• hypersensitivity reactions,
• seizures,
• agitation,
• confusion,
• hepatitis,
• and muscle pain.

Is Zovirax addictive?

No information provided

What drugs interact with Zovirax?

Drug-Drug Interactions

No clinically significant interactions have been identified.

Acyclovir is primarily eliminated through the urine. Concurrent use of drugs that compete for renal tubular secretion may increase acyclovir plasma concentrations. Probenecid and cimetidine can increase acyclovir levels and reduce its renal clearance.

Similar increases in plasma levels have been seen when acyclovir is coadministered with mycophenolate mofetil, an immunosuppressant.

Drug-Food Interactions

There is no known interaction with food.

Drug-Herb Interactions

No interactions with herbal products have been established.

Drug-Laboratory Test Interactions

No interactions with laboratory tests have been established.

Zovirax side effects list for healthcare professionals

Adverse Drug Reaction Overview

The most frequent adverse reactions associated with the use of Zovirax are headache and nausea.

Neurological side effects have also been reported in rare instances, especially in elderly patients and those with renal impairment. Discontinuation of treatment generally reverses these effects.

Clinical Trial Adverse Drug Reactions

Note: Adverse reaction rates observed in clinical trials may not reflect rates in practice.

Treatment of Herpes Simplex

Short-term administration: The most frequent adverse reactions reported during clinical trials of oral Zovirax in patients with genital herpes are nausea and vomiting.

Suppression of Herpes Simplex

Long-term administration: The most frequent adverse events reported in a clinical trial for the prevention of recurrences with continuous administration of oral Zovirax are nausea, diarrhea, headache, rash, paresthesia, and asthenia.

Adverse events are unlikely to require discontinuation of therapy.

Herpes Zoster

The most frequent adverse reactions reported during clinical trials of herpes zoster treatment with oral Zovirax or placebo are malaise, nausea, headache, vomiting, and diarrhea.

Chickenpox

The most frequent adverse events reported during clinical trials of chickenpox treatment with oral Zovirax or placebo are diarrhea.

Less Common Clinical Trial Adverse Drug Reactions (< 1%)

Other adverse reactions reported in less than 1% of patients receiving Zovirax in any clinical trial included abdominal pain, anorexia, constipation, dizziness, edema, fatigue, flatulence, inguinal adenopathy, insomnia, leg pain, medication taste, skin rash, sore throat, spasmodic hand movement, and urticaria.

Abnormal Hematologic And Clinical Chemistry Findings

No clinically significant changes in laboratory values have been observed in clinical trials for the treatment of chickenpox, zoster, and genital herpes with Zovirax.

Post-Market Adverse Drug Reactions

The following events have been reported voluntarily during post-market use of Zovirax. These events have been chosen for inclusion due to their seriousness, frequency of reporting, potential causal connection to Zovirax, or a combination of these factors. It is not possible to estimate their frequency.

General: Fever, headache, pain, and peripheral edema.

Nervous: Dizziness, paresthesia, agitation, confusion, tremor, ataxia, dysarthria, hallucinations, psychotic symptoms, convulsions, somnolence, encephalopathy, and coma have been reported. These events are generally reversible and usually reported in patients with renal impairment or other predisposing factors. Older adults may experience more severe symptoms.

Digestive: Diarrhea, gastrointestinal distress, and nausea.

Hematogical and Lymphatic: Anemia, leukopenia, lymphadenopathy, and thrombocytopenia.

Hypersensitivity and Skin: Alopecia, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, rashes including photosensitivity, pruritus, urticaria, dyspnea, angioedema, and anaphylaxis.

Hepatobiliary Tract and Pancreas: Reversible hyperbilirubinemia, elevated liver-related enzymes, hepatitis, and jaundice.

Musculoskeletal: Myalgia.

Special Senses: Visual abnormalities.

Urogenital: Elevated blood creatinine and blood urea nitrogen (BUN), acute renal failure, renal pain, and hematuria have been reported. Renal pain may be associated with renal failure.

Summary

Zovirax (acyclovir) is an antiviral drug that inhibits the replication of herpes viruses. Common side effects include nausea, vomiting, diarrhea, and headache. There is limited information on the use of Zovirax in pregnant women and caution is advised when breastfeeding.