Skip to Content

Zovirax Side Effects

Generic Name: acyclovir

Note: This page contains side effects data for the generic drug acyclovir. It is possible that some of the dosage forms included below may not apply to the brand name Zovirax.

For the Consumer

Applies to acyclovir: capsule, powder for solution, solution, suspension, tablet

Other dosage forms:

As well as its needed effects, acyclovir (the active ingredient contained in Zovirax) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking acyclovir, check with your doctor immediately:

More common: - For acyclovir injection only
  • Pain, swelling, or redness at place of injection
Less common:
  • Abdominal or stomach pain
  • decreased frequency of urination or amount of urine
  • increased thirst
  • loss of appetite
  • nausea or vomiting
  • unusual tiredness or weakness
Rare
  • Black, tarry stools
  • blood in urine or stools
  • chills, fever, or sore throat
  • confusion
  • convulsions (seizures)
  • hallucinations (seeing, hearing, or feeling things that are not there)
  • hives
  • pinpoint red spots on skin
  • trembling
  • unusual bleeding or bruising
Frequency not determined
  • Bleeding or oozing from puncture sites or mucous membranes (bowel, mouth, nose, or urinary bladder), continuing
  • blistering, peeling, or loosening of skin
  • bluish coloring, especially of the hands and feet
  • blurred vision
  • bruising at the place of injection
  • changes in facial skin color
  • changes in vision
  • clumsiness
  • coughing
  • decreased consciousness
  • difficulty in breathing or swallowing
  • dizziness or feeling faint, severe
  • fast heartbeat
  • irritability
  • itching or skin rash
  • large hive-like swelling on face, eyelids, lips, tongue, throat, hands, legs, feet, sex organs
  • mood or mental changes
  • muscle cramps, pain, or weakness
  • pale skin
  • red or irritated eyes
  • sense of agitation or uneasiness
  • shakiness and unsteady walk
  • sores, ulcers, or white spots in mouth or on lips
  • swelling of eyelids, face, feet, hands, lower legs or lips
  • swollen, painful, or tender lymph nodes (glands) in neck, armpit, or groin
  • unsteadiness or other problems with muscle control or coordination
  • yellow eyes or skin

Minor Side Effects

Some acyclovir side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common: - Especially seen with high doses
  • General feeling of discomfort or illness
Less common: - Especially seen with long-term use or high doses
  • Diarrhea
  • headache
Frequency not determined
  • Burning, prickling, or tingling sensations
  • drowsiness
  • loss of hair

For Healthcare Professionals

Applies to acyclovir: buccal tablet, compounding powder, intravenous powder for injection, intravenous solution, oral capsule, oral suspension, oral tablet

General

The more commonly reported adverse reactions include malaise, nausea, vomiting, diarrhea, and headache.[Ref]

Gastrointestinal

Nausea and vomiting are more frequent in elderly subjects.[Ref]

Common (1% to 10%): Nausea, vomiting, diarrhea, abdominal pain, gingival pain (buccal tablet), aphthous stomatitis (buccal tablet)
Uncommon (0.1% to 1%): Sore throat
Postmarketing reports: Gastrointestinal distress[Ref]

Renal

Rare (0.01% to 0.1%): Elevated blood urea nitrogen, elevated creatinine,
Very rare (less than 0.01%): Acute renal failure, renal pain
Frequency not reported: Crystalluria, renal impairment
Postmarketing reports: Renal failure, hematuria[Ref]

Renal pain may be associated with renal failure and crystalluria. Renal impairment is generally reversible but may progress to acute renal failure.[Ref]

Local

Common (1% to 10%): Application site pain and application site irritation, local inflammation at injection site, phlebitis
Frequency not reported: Tissue necrosis[Ref]

Severe local inflammatory reactions, including tissue necrosis, have occurred following infusion into extravascular tissues. Application site pain and application site irritation have occurred with the buccal tablets.[Ref]

Nervous system

Dizziness, somnolence, and coma more frequent in elderly subjects.[Ref]

Common (1% to 10%): Headache, dizziness
Very rare (less than 0.01%): Ataxia, coma, convulsions, encephalopathy, dysarthria
Frequency not reported: Giddiness, shaking, taste disturbance, medication taste
Postmarketing reports: Decreased consciousness, delirium, paresthesia, seizure, tremors[Ref]

Dermatologic

Common (1% to 10%): Erythema, rashes (including photosensitivity), pruritus, hives
Uncommon (0.1% to 1%): Urticaria, accelerated diffuse hair loss
Frequency not reported: Diaphoresis
Postmarketing reports: Alopecia, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis[Ref]

Cardiovascular

Frequency not reported: Palpitation, chest pain
Postmarketing reports: Hypotension, peripheral edema[Ref]

Hematologic

Very rare (less than 0.01%): Anemia, leukopenia, thrombocytopenia, neutropenia
Frequency not reported: Hematologic changes including megaloblastic anemia
Postmarketing reports: Leukocyclastic vasculitis, lymphadenopathy, disseminated intravascular coagulation, hemolysis[Ref]

Hepatic

Rare (0.01% to 0.1%): Reversible bilirubin and liver related enzymes
Very rare (less than 0.01%): Hepatitis, jaundice
Postmarketing reports: Hyperbilirubinemia[Ref]

Hypersensitivity

Rare (0.01% to 0.1%): Anaphylaxis
Frequency not reported: Angioedema[Ref]

Ocular

Frequency not reported: Pars planitis
Postmarketing reports: Visual abnormalities[Ref]

Musculoskeletal

Uncommon (0.1% to 1%): Leg pain
Postmarketing reports: Myalgia[Ref]

Other

Common (1% to 10%): Lethargy, fatigue, fever
Frequency not reported: Vertigo
Postmarketing reports: Fever[Ref]

Genitourinary

Frequency not reported: Menstrual abnormalities, abnormal urinalysis (characterized by an increase in formed elements in urine sediment) anuria, dysuria, hematuria[Ref]

Metabolic

Uncommon (0.1% to 1%): Anorexia
Frequency not reported: Thirst[Ref]

Psychiatric

Hallucinations, psychosis, confusion, aggressive behavior, agitation may be more marked in older adults and those with renal impairment.[Ref]

Very rare (less than 0.01%): Agitation, confusion, hallucinations, psychotic symptoms
Frequency not reported: Depression, insomnia
Postmarketing reports: Aggressive behavior[Ref]

Respiratory

Rare (0.01% to 0.1%): Dyspnea[Ref]

References

1. "Product Information. Acyclovir (acyclovir)." West-Ward Pharmaceuticals Corporation (previously Roxane Laboratories Inc), Columbus, OH.

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

4. "Product Information. Sitavig (acyclovir)." Innocutis Holdings LLC, Charleston, SC.

5. "Product Information. Zovirax (acyclovir)." Mylan Pharmaceuticals Inc, Morgantown, WV.

It is possible that some side effects of Zovirax may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.

Hide