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Homebreast cancerZovirax (acyclovir) vs. Abreva (docosanol): Herpes Drug Side Effects

Zovirax (acyclovir) vs. Abreva (docosanol): Herpes Drug Side Effects

Zovirax (Acyclovir) vs. Abreva Cream (docosanol): What’s the difference?

What is acyclovir? What is Abreva?

Acyclovir is a nucleoside analogue, a type of antiviral drug, used to treat forms of the herpes virus including cold sores, genital herpes, varicella zoster (chickenpox), herpes zoster (shingles), herpes simplex encephalitis, and mucocutaneous herpes simplex virus infection. Acyclovir works by interfering with viral replication against herpes viruses, including herpes simplex 1 and 2 (cold sores and genital herpes), varicella-zoster (shingles and chickenpox), and Epstein-Barr virus (mononucleosis). Viruses invade living cells and reproduce themselves, usually at the expense of the host cell. Acyclovir is converted to an active form by the virus itself, and the virus then uses the active form of acyclovir rather than the nucleoside it normally uses to manufacture DNA, an essential component of viral replication. Active acyclovir incorporation into new viral DNA stops the production of the DNA. Virally infected cells absorb more acyclovir than normal cells and convert more of it to the active form, which prolongs its antiviral activity.

Abreva Cream (docosanol) is a topical (for the skin) cold sore medicine that penetrates deep into the skin and starts to work immediately to block the virus and provide a barrier for healthy cells. It is the only nonprescription cold sore medicine approved by the FDA to shorten healing time.


Condoms are the best protection from sexually transmitted diseases (STDs).
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What are the side effects of acyclovir and Abreva?


The most common side effects are

Other reported side effects include:


Side effects of Abreva are uncommon and may include:

  • skin itching,
  • rash, and
  • redness where the medicine is applied

What is the dosage of acyclovir vs. Abreva?


Acyclovir may be taken with or without food.

  • Adult oral doses for treating genital herpes are 200 mg every 4 hours (5 times daily) for 7-10 days or 400 mg three times daily for 5-10 days.
  • Herpes Zoster (shingles) is treated with 800 mg every 4 hours (5 times daily) for 7 to 10 days.
  • The dose for treating chicken pox is 800 mg 4 times daily. The usual adult intravenous dose is 5-10 mg/kg every 8 hours for 7-10 days.


Directions: adults and children 12 years or over:

  • wash hands before and after applying cream
  • apply to affected area on face or lips at the first sign of cold sore/fever blister (tingle).
  • early treatment ensures the best results
  • rub in gently but completely
  • use 5 times a day until healed

children under 12 years:

  • ask a doctor

Are acyclovir and Abreva safe to take while pregnant or breastfeeding?


There are no adequate studies of acyclovir in pregnant women. In a patient registry of women who used acyclovir during the first trimester, the rate of birth defects was similar to the rate of birth defects in the general population.

Acyclovir is excreted in breast milk, and a significant amount may be transferred to the infant.


There is no information about Abreva and pregnancy or breastfeeding safety.


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