Several medications can shorten the duration of outbreaks. Prescription valacyclovir (Valtrex) may be the best choice for treatment because it requires fewer doses and costs less than some other prescription remedies. An over-the-counter drug containing docosanol cream (Abreva) is slightly less effective but it’s cheaper and can help ease the pain. Contact your physician if the sores don’t heal within two weeks. And if you have more than six outbreaks a year, ask your doctor about taking acyclovir (Zovirax) for prevention, since it can reduce episodes by up to 80 percent.