Fever blisters take up to two weeks to heal, according to the Mayo Clinic. If a fever blister lasts longer than two weeks, a physician should be contacted.
Although fever blisters heal on their own, a physician may prescribe an antiviral, such as acyclovir, valacyclovir and famciclovir, to speed up the process, according to the Mayo Clinic. Other treatments can also ease symptoms and shorten outbreaks. Docosanol, an over-the-counter cream, can shorten outbreaks by as much as a day. As an alternative remedy, lemon balms with at least 1 percent of lemon extract may shorten healing time.
To manage symptoms, a cool, wet washcloth can improve swelling, according to WebMD. Over-the-counter medications, such as ibuprofen and acetaminophen, may reduce cold sore pain.