Cold sores, also known as fever blisters, oral herpes and herpes labialis, are caused by the herpes simplex virus. In the June 9, 2008, issue of "Archives of Internal Medicine," Northeastern Ohio University dermatologist Christina Cernik explains that cold sores begin as tiny, painful blisters filled with clear or cloudy yellow fluid. After three or four days, these blisters rupture, leaving behind a weeping, open sore that takes another six to 10 days to disappear. Aloe vera, a natural compound that has been used to heal skin problems for more than 2,000 years, may help heal cold sores alone or in conjunction with prescription antiviral drugs.
Aloe vera--also known as cape, zanzibar, socotrine, curacao or Barbados aloe--is a sticky green gel found inside the leaves of the cactus plant Aloe barbadensis. The University of Pittsburgh Medical Center, or UPMC, says that aloe has been used since prehistoric times for the treatment of burns, infections and other skin problems. Aloe vera is different from aloe, which is a resinous substance harvested from the skin of Aloe barbadensis leaves. The latter is ingested orally while aloe vera is applied topically.
A study published in the December 1991 journal “Antimicrobial Agents and Chemotherapy,” found that aloe vera does, in fact, inactivate a variety of viruses in test tubes, including the herpes simplex virus that causes cold sores. However, compounds that work well in test tubes do not always work well in people. As of November 2010, the National Library of Medicine lists no studies that prove aloe vera produces similar effects on cold sores in people.
Despite the lack of clinical studies supporting the use of aloe vera in people with cold sores, Academy of General Dentistry spokesperson Kenton A. Ross, D.M.D., recommends aloe vera products for people with oral health problems, including cold sores. According to the Academy, when applied three times per day to cold sores on or around the mouth, aloe vera hastens healing and quells pain without the bad taste or stinging sensation that accompanies numbing agents and other over-the-counter cold sore products.
According to the University of Michigan Health System, side effects of aloe vera are uncommon and include burning, redness and rash. People who experience these side effects should remove the product with gentle soap and water, pat dry and allow the skin to rest. If symptoms become severe or persist longer than three days, the affected person should see a doctor. Aloe vera should not be used on women who are pregnant or nursing, children and people with a history of allergies, except as directed by a doctor.
Many over-the-counter lip balms, lotions and ointments list aloe vera as an active ingredient. Ross and the Academy of General Dentistry do not endorse any specific product or concentration of aloe vera. UPMC lists several studies that used concentrations of 0.5 percent aloe vera for conditions other than cold sores. Ideally, patients should choose aloe vera products that also contain sunscreen because they protect against ultraviolet light from the sun, which is a common cold sore trigger.
Aloe vera products--as with all other herbal remedies--are not evaluated by the Food and Drug Administration for safety, effectiveness or purity. They do not replace conventional medical treatments for cold sores or any other condition and people who use them should share this information with all health care providers. People with severe, frequent or long-lasting--longer than two weeks--cold sores should consult a physician because these may be signs of another underlying condition, such as immune system problems or secondary bacterial infections.