Cold sores are a common viral infection. They are tiny, fluid-filled blisters on and around your lips. These blisters are often grouped together in patches. After the blisters break, a crust forms over the resulting sore. Cold sores usually heal in two to four weeks without leaving a scar.
Cold sores spread from person to person by close contact, such as kissing. They’re caused by a herpes simplex virus (HSV-1) closely related to the one that causes genital herpes (HSV-2). Both of these viruses can affect your mouth or genitals and can be spread by oral sex. Cold sores are contagious even if you don’t see the sores.
There’s no cure for HSV infection, and the blisters may return. Antiviral medications can help cold sores heal more quickly and may reduce how often they return.
A cold sore usually passes through several stages:
- Tingling and itching. Many people feel an itching, burning or tingling sensation around their lips for a day or so before a small, hard, painful spot appears and blisters erupt.
- Blisters. Small fluid-filled blisters typically break out along the border where the outside edge of the lips meets the skin of the face. Cold sores can also occur around the nose or on the cheeks.
- Oozing and crusting. The small blisters may merge and then burst, leaving shallow open sores that will ooze fluid and then crust over.
Signs and symptoms vary, depending on whether this is your first outbreak or a recurrence. They can last several days, and the blisters can take two to four weeks to heal completely. Recurrences typically appear at the same spot each time and tend to be less severe than the first outbreak.
During first-time outbreaks, some people also experience:
- Painful eroded gums
- Sore throat
- Muscle aches
- Swollen lymph nodes
Children under 5 years old may have cold sores inside their mouths and the lesions are commonly mistaken for canker sores. Canker sores involve only the mucous membrane and aren’t caused by the herpes simplex virus.
When to see a doctor
Cold sores generally clear up without treatment. See your doctor if:
- You have a weakened immune system
- The cold sores don’t heal within two weeks
- Symptoms are severe
- You have frequent recurrences of cold sores
- You experience irritation in your eyes
Cold sores generally clear up without treatment in two to four weeks. Several types of prescription antiviral drugs may speed the healing process. Examples include:
- Acyclovir (Xerese, Zovirax)
- Valacyclovir (Valtrex)
- Famciclovir (Famvir)
- Penciclovir (Denavir)
Some of these products are packaged as pills to be swallowed. Others are creams to be applied to the sores several times a day. In general, the pills work better than the creams. For very severe infections, some antiviral drugs can be given with an injection.
To ease the discomfort of a cold sore, you may want to try the following tips:
- Apply a cold sore ointment. Docosanol (Abreva) is an over-the-counter cream for cold sores. It must be applied frequently and may shorten an outbreak by a few hours or a day.
- Try other cold sore remedies. Some over-the-counter preparations contain a drying agent, such as alcohol, that may speed healing.
- Use lip balms and cream. Protect your lips from the sun with a zinc oxide cream or lip balm with sunblock. If your lips become dry, apply a moisturizing cream.
- Apply a cool compress. A cool, damp cloth may reduce redness, help remove crusting and promote healing.
- Apply pain-relieving creams. Over-the-counter creams with lidocaine or benzocaine may offer some pain relief.