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Zovirax Oral Precautions and Side Effects


IMPORTANT NOTE: The following information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist or other healthcare professional. It should not be construed to indicate that use of the drug is safe, appropriate or effective for you. Consult your healthcare professional before using this drug.

Table of Contents

Generic Name: ACYCLOVIR - ORAL
Pronounced: (ay-SYE-kloe-vir)

Zovirax Oral Side Effects

Nausea may occur. If nausea persists or worsens, tell your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor immediately if any of these unlikely but serious side effects occur:

  • dizziness
  • drowsiness
  • signs of kidney problems (such as a change in the amount of urine, unusual back/side pain)
  • mental/mood changes (such as agitation, confusion, hallucinations)
  • shaky/unsteady movement
  • trouble speaking


This medication may rarely cause a life-threatening disorder that affects the blood cells, kidneys, and other parts of the body. This disorder is more likely to occur if you have conditions related to a weakened immune system (such as HIV disease, bone marrow transplant, kidney transplant). Seek immediate medical attention if any of these rare but serious side effects occur:

  • extreme tiredness
  • slow/fast/irregular heartbeat
  • easy bruising/bleeding
  • new fever
  • bloody/dark urine
  • severe stomach/abdominal pain
  • yellowing eyes/skin
  • sudden vision changes
  • loss of consciousness
  • seizures


A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including:

  • rash
  • itching/swelling (especially of the face/tongue/throat)
  • severe dizziness
  • trouble breathing


This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Zovirax Oral Precautions

Before taking acyclovir, tell your doctor or pharmacist if you are allergic to it; or to valacyclovir; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

  • kidney problems
  • conditions related to a weakened immune system (such as HIV disease, bone marrow transplant, kidney transplant)


This drug may rarely make you dizzy or drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.

Kidney function declines as you grow older. This medication is removed by the kidneys. Older adults may be more sensitive to the side effects of the drug, especially kidney problems (change in the amount of urine, back/side pain), dizziness, drowsiness, and mental/mood changes (such as confusion, hallucinations, loss of consciousness).

Acyclovir does not protect against the spread of genital herpes. To lower the chance of giving herpes to your partner, do not have sexual contact during an outbreak or if you have symptoms. You can spread genital herpes even if you do not have symptoms. Therefore, always use an effective barrier method (latex or polyurethane condoms/dental dams) during all sexual activity. Consult your doctor or pharmacist for more details.

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This medication passes into breast milk. However, this drug is unlikely to harm a nursing infant. Consult your doctor before breast-feeding.


CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.
Copyright 2007 First DataBank, Inc.

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