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Valtrex (valacyclovir) vs. Abreva (docosanol): What’s the difference?
- Valtrex (valacyclovir) and Abreva (docosanol) are antiviral drugs used to treat cold sores (herpes labialis).
- Valtrex is also used to treat shingles (herpes zoster) and genital herpes (herpes simplex genitalis) infections.
- Abreva is available over-the-counter (OTC) and as a generic.
- Valtrex is an oral drug and Abreva is a topical (for the skin) medication.
- Side effects of Valtrex that are different from Abreva include headache, nausea, vomiting, abdominal pain, cold symptoms, increased liver enzymes, reduction of white blood cells, diarrhea, rash, joint pain, and dizziness.
- Side effects of Abreva that are different from Valtrex include application site redness or swelling.
What is Valtrex? What is Abreva?
Valtrex (valacyclovir) is an antiviral drug used to treat shingles (herpes zoster) and genital herpes (herpes simplex genitalis) infections, and cold sores (herpes labialis). Valtrex is a nucleoside analog that mimics one of the building blocks of DNA. It stops the spread of herpes virus in the body by preventing the replication of viral DNA that is necessary for viruses to multiply. Other nucleoside analogs include acyclovir (Zovirax) and famciclovir (Famvir). Valacyclovir is actually a "prodrug," in that it is not active itself. Rather, it is converted to acyclovir in the body, and it is the acyclovir that is active against the viruses. (Acyclovir itself is available as a topical, oral, and intravenous medication.) Valacyclovir thus is active against the same viruses as acyclovir, but valacyclovir has a longer duration of action than acyclovir and can be taken fewer times each day.
Abreva (docosanol) is used to treat "cold sores/fever blisters" (herpes labialis). It can speed up healing of the sores and decrease symptoms (such as tingling, pain, burning, itching). It works by blocking the virus that causes the cold sores (herpes simplex) from entering the healthy skin cells and growing in number. Abreva does not cure herpes and does not prevent passing the infection to someone else. It does not prevent a future occurrence. Abreva is not used to treat canker sores (sores found commonly in the mouth), shingles, or genital herpes.
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What are the side effects of Valtrex and Abreva?
Valtrex
The side effect profile of Valtrex is similar to that of acyclovir (Zovirax).
Common side effects are:
- Headache
- Nausea
- Vomiting
- Abdominal pain
- Cold symptoms
- Increased liver enzymes
- Reduction of white blood cells
Other important side effects are:
More serious side effects include central nervous system side effects which are more likely to happen in the elderly, for example:
- Agitation
- Hallucinations
- Confusion
- Delirium
- Depression
- Increased heart rate (tachycardia)
- Seizures
- Encephalopathy (a disorder of the brain)
- Decreased number of blood platelets
- Increased heart rate
- High blood pressure (hypertension)
Abreva
Side effects of Abreva are uncommon and may include:
- Skin itching
- Rash
- Redness where the medicine is applied
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What is the dosage of Valtrex vs. Abreva?
Valtrex
- Valtrex may be taken with or without food.
- In people with kidney disease, doses need to be reduced.
- For the treatment of herpes zoster (shingles), the usual dose is 1 gram 3 times a day for 7 days. Treatment should begin at the first symptom and is most effective if started within 48 hours of the onset of rash.
- The dose for chickenpox is 20 mg/kg 3 times daily for 5 days (maximum dose is 1000 mg 3 times daily) and treatment should start at the earliest sign or symptom.
- For the treatment of an initial episode of genital herpes, the usual dose is 1 gram (1000 mg) twice daily for 10 days. For the treatment of recurrent genital herpes, the usual dose is 500 mg twice daily for 3 days. For best results, treatment should be initiated within 12 hours of the start of symptoms.
- The dose for cold sores is 2000 mg (2 grams) every 12 hours for 1 day.
Abreva
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.
What drugs interact with Valtrex and Abreva?
Valtrex
Probenecid (Benemid) and cimetidine (Tagamet) may reduce the kidney's clearance of Valtrex, leading to higher concentrations in the blood. This may lead to side effects of Valtrex.
Abreva
No information provided.
Are Valtrex and Abreva safe to use while pregnant or breastfeeding?
Valtrex
Valtrex showed no effects on the fetus in animal studies; however, there has been no adequate evaluation of valacyclovir or (acyclovir) in pregnant women. The incidence of birth defects in women taking acyclovir is about the same as in the general population. Valtrex should only be used during pregnancy when the benefits to the mother outweigh risks to the fetus.
It is not known whether Valtrex is excreted into breast milk. It is known, however, that among women taking acyclovir, concentrations of acyclovir in breast milk are about four times higher than in the mother's blood. The safety of valacyclovir in breastfeeding infants has not been established. Methods other than breastfeeding should be considered if valacyclovir must be taken while nursing.
Abreva
There is no information about Abreva and pregnancy or breastfeeding safety.