Home > Patients & Visitors > Health Library > Oral Antivirals for Cold Sores
Most cold sores heal on their own without prescription medicines. But some antiviral medicines (such as acyclovir or famciclovir) when taken orally (tablets) may
be helpful in reducing the frequency and severity of attacks of
Doctors may prescribe oral antiviral medicines that
can be taken daily to prevent future outbreaks of cold sores. These medicines
may also be given during periods of increased risk of getting cold sores
(such as during cosmetic surgery or sun exposure).
Oral antivirals work best in treating recurring cold sores
if they are taken within 24 to 48 hours of an outbreak of cold
Pregnant or nursing women should seek their doctors' advice prior to
taking antiviral medicines. Those with kidney problems may be advised to take
Some examples of oral antiviral medicines prescribed to treat cold
sores include the following:
Acyclovir (Zovirax) tablets may slightly shorten the duration of pain and the healing time of a first attack of cold sores.footnote 1
Common side effects of acyclovir tablets include nausea, diarrhea, and headache.
A lower dose of oral acyclovir is needed for people who have
reduced kidney function.
Famciclovir (Famvir) is sometimes used to treat the herpes virus that causes
cold sores and genital herpes (as well as the virus that causes shingles). This medicine is available only by
prescription and is taken orally in tablet form.
If you are pregnant or nursing, you should talk with your doctor
before taking famciclovir.
This medicine is not recommended for people who have had an
allergic reaction to it in the past.
Possible mild side effects include itching, fever, headache,
fatigue, nausea, or diarrhea.
Valacyclovir (Valtrex) capsules are available by prescription only. It is absorbed by the body much better than
some other antiviral medicines (such as acyclovir).
Possible side effects include skin rash,
allergic reaction, headache, dizziness,
Children, pregnant women, and people who have HIV or who have had
bone marrow or kidney transplants should talk with their doctors before taking
Worrall G (2009). Herpes labialis, search date February 2009. Online version of BMJ Clinical Evidence: http://www.clinicalevidence.com.
ByHealthwise StaffPrimary Medical ReviewerE. Gregory Thompson, MD - Internal MedicineAdam Husney, MD - Family Medicine
Current as ofMay 27, 2016
Current as of:
May 27, 2016
E. Gregory Thompson, MD - Internal Medicine & Adam Husney, MD - Family Medicine
To learn more about Healthwise, visit Healthwise.org.
© 1995-2016 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
Our interactive Decision Points guide you through making key health decisions by combining medical information with your personal information.
You'll find Decision Points to help you answer questions about:
Get started learning more about your health!
Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups and pregnancy.
Feeling under the weather?
Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.