Slideshows Images Quizzes

Zovirax

Last reviewed on RxList: 1/7/2016
Zovirax Side Effects Center

Last reviewed on RxList 9/1/2016

Zovirax (acyclovir) is a synthetic nucleoside analogue that interferes with the replication of herpes viruses used to treat

Zovirax is available in generic form. Side effects of Zovirax include: Serious side effects of Zovirax include renal function problem.

Zovirax tablets are available in 200, 400 and 800 mg strengths and as a liquid suspension with 200 mg strength per 5 ml. Usual doses are 800 mg every 4 hours, 5 times a day for 10 days for shingles; doses for genital herpes infection are the same interval but start with 200 mg. Doses for chickenpox is the same as shingles except it goes for only 5 days for adults; for children ages 2 and up are weight based (20 mg per Kg) up to 40 Kg, 5 times a day for 5 days. Over 40 Kg, the person gets the adult dose for 5 days. Zovirax may interact with probenecid. Tell your doctor all medications and supplements you use. There are no good studies on pregnant women. Zovirax may be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Caution is advised with use of Zovirax in women who are breastfeeding since the drug is secreted in breast milk. Safety and efficacy has not been studied in pediatric patients below the age of 2 years.

Our Zovirax Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Zovirax Consumer Information

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any of these serious side effects:

  • pain in your lower back;
  • urinating less than usual or not at all;
  • easy bruising or bleeding; or
  • unusual weakness.

Less serious side effects may include:

  • nausea, vomiting, diarrhea, loss of appetite, stomach pain;
  • headache, feeling light-headed; or
  • swelling in your hands or feet.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Zovirax (Acyclovir)

Zovirax Professional Information

SIDE EFFECTS

Adverse Drug Reaction Overview

The most frequent adverse reactions associated with the use of ZOVIRAX® (acyclovir) are headache and nausea.

Neurological side effects have also been reported in rare instances. Elderly patients and patients with a history of renal impairment are at increased risk of developing these effects. In the reported cases, these reactions were generally reversible on discontinuation of treatment (see WARNINGS AND PRECAUTIONS and ADVERSE REACTIONS, Post-Market Adverse Drug Reactions).

Clinical Trial Adverse Drug Reactions

Because clinical trials are conducted under very specific conditions the adverse reaction rates observed in the clinical trials may not reflect the rates observed in practice and should not be compared to the rates in the clinical trials of another drug. Adverse drug reaction information from clinical trials is useful for identifying drug-related adverse events and for approximating rates.

Treatment of Herpes Simplex

Short-term administration (5-10 days): The most frequent adverse reactions reported during clinical trials of treatment of genital herpes with oral ZOVIRAX® in 298 patients are listed in Table 1.

Table 1 : Adverse Reactions Reported in Clinical Trials of Treatment of Genital Herpes with Acyclovir

Adverse Reactions Total %
Nausea and/or Vomiting 8 2.7

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 400 mg (two 200 mg capsules) 2 times daily are listed in Table 2.

Table 2 : Adverse Reactions Reported in a Clinical Trial for the Prevention of Recurrences of Genital Herpes with Acyclovir

Adverse Reactions 1st Year
(n=586) %
2nd Year
(n=390) %
3rd Year
(n=329) %
Nausea 4.8    
Diarrhea 2.4    
Headache 1.9 1.5 0.9
Rash 1.7 1.3  
Paresthesia   0.8 1.2
Asthenia     1.2

Evidence so far from clinical trials suggests that the severity and frequency of adverse events is unlikely to necessitate discontinuation of therapy.

Herpes Zoster

The most frequent adverse reactions reported during three clinical trials of treatment of herpes zoster (shingles) with 800 mg of oral ZOVIRAX® 5 times daily for 7 or 10 days or placebo are listed in Table 3.

Table 3 : Adverse Reactions Reported in Clinical Trials of Treatment of Herpes Zoster

Adverse Reactions ZOVIRAX®
(n=323) %
Placebo
(n=323) %
Malaise 11.5 11.1
Nausea 8.0 11.5
Headache 5.9 11.1
Vomiting 2.5 2.5
Diarrhea 1.5 0.3

Chickenpox

The most frequent adverse events reported during three clinical trials of treatment of chickenpox with oral ZOVIRAX® or placebo are listed in Table 4.

Table 4 : Adverse Reactions Reported in Clinical Trials of Treatment of Chickenpox

Adverse Reactions ZOVIRAX®
(n=495)%
Placebo
(n=498)%
Diarrhea 3.2 2.2

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 and zoster, and for the treatment and suppression of genital herpes with ZOVIRAX®.

Post-Market Adverse Drug Reactions

The following events have been reported voluntarily during post-market use of ZOVIRAX® in clinical practice. These events have been chosen for inclusion due to either their seriousness, frequency of reporting, potential causal connection to ZOVIRAX® or a combination of these factors. Post-market adverse events are reported spontaneously from a population of unknown size, thus estimates of frequency cannot be made.

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 with other predisposing factors (see WARNINGS AND PRECAUTIONS). These symptoms may be marked, particularly in older adults.

Digestive: Diarrhea, gastrointestinal distress and nausea.

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

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

Hepatobiliary Tract and Pancreas: Reports of reversible hyperbilirubinemia and 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 (see WARNINGS AND PRECAUTIONS).

Read the entire FDA prescribing information for Zovirax (Acyclovir)

Related Resources for Zovirax

Read the Zovirax User Reviews »

© Zovirax Patient Information is supplied by Cerner Multum, Inc. and Zovirax Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

Health Solutions From Our Sponsors