A fever blister, or cold sore, can last from 10 to 14 days. Fever blisters usually occur in groups and cause red, swollen, and sore wounds. They commonly form near the mouth or on other areas of the face, but they may also appear on the tongue or gums.

Fever blisters may release a clear fluid that scabs after a few days. During this time, fever blisters are most contagious. However, the virus that causes fever blisters can continue to be contagious even when there are no blisters visible.

The cause of fever blisters is the herpes simplex virus. If you’re having an outbreak, know that it’s very commonplace. Worldwide, more than 90 percent of the adult population has one or both forms of this virus (HSV-1 and HSV-2). In the United States, about 65 percent of the population has been exposed to HSV-1.

A fever blister flare-up can heal without treatment, but there are many effective ways to help relieve the pain and promote healing. This includes at-home remedies and prescription medications.

Studies have shown some essential oils may have antiviral activity against HSV-1. Essential oils and topical treatments can irritate your skin, so you should always test a small area of the skin first before use.

You’ll also need to dilute essential oils with a carrier oil (vegetable or nut oil). The ratio is about one drop of essential oil per one teaspoon of carrier oil. Use a clean cotton swab or pad when applying these essential oils, which helps avoid contamination and reinfection.

Here are nine natural home remedies for fever blisters:

1. Ice

Ice can help treat inflammation by reducing blood flow to the area. It also numbs the area so that there’s less pain. But this treatment is only temporary and it does not affect the virus in any way or promote healing.

How to use: To treat a cold sore, wrap an ice pack with a towel or cloth. Place it on the cold sore for at least 5 minutes and no more than 15 minutes. Never apply ice directly to the skin as this can cause significant injury.

2. Lemon balm (Melissa officinalis)

One 2012 study found that Melissa officinalis could kill the herpes simplex virus in some cases and affect how the virus attaches to host cells.

How to use: Apply a cream, ointment, or lip balm containing lemon balm to the affected area several times per day. You may also put diluted essential oil on a cotton ball and hold it on the sores for a few minutes. Continue using lemon balm for a few days after your sores have healed.

3. L-lysine

L-lysine is an amino acid that may help shorten the duration of a fever blister. People report benefits from taking this supplement as a preventative and treatment.

According to Harvard Health Publications, lysine can inhibit the amino acid that promotes the growth of the fever blisters. However, more research is needed to confirm its effectiveness. It may also have a role in limiting fever blister outbreaks.

How to use: Research doses range from 500 to 3,000 milligrams (mg). Follow the recommendation on the package.

Shop for L-lysine supplements online.

4. Zinc therapy

Zinc is an essential mineral that can help wounds heal, and topical zinc may help with fever blisters. One 2001 study found that a cream containing zinc oxide and glycine shortened the duration of cold sores compared to a placebo cream. A more recent study showed zinc oxide may also have a role in preventing the herpes simplex virus from entering cells.

How to use: A 2005 pilot study saw a reduced frequency of outbreaks when participants took zinc sulfate supplements. They took 22.5 mg twice a day for two months, skipped six months, then twice a day for another two months. For topical treatments, you’ll want to apply a zinc oxide cream four times a day.

Shop for zinc cream online.

5. Oregano oil

On a cellular level, oregano oil is shown to inhibit different animal and human viruses, including herpes. It’s unclear what dose is needed to provide benefits.

How to use: Apply diluted oregano oil to a cotton ball and apply to the affected area. Repeat several times throughout the day, and continue treatment until your blisters heal completely.

6. Licorice extract

Licorice root is gaining popularity as a treatment option for cold sores. A 2014 cell study found more evidence of licorice’s antiherpetic activity, but its effects on the virus in humans still need more research.

How to use: You can apply diluted licorice extract, like this one from Nature's Answer, on your fever blister with a cotton swab or finger tips. If you’re using pills, make it into a paste with coconut or almond oil and apply to the affected area. Talk to your doctor before taking licorice root orally, as it may cause unintended side effects.

7. Tea tree oil

A review of tea tree oil studies suggest that it may be a useful antiviral treatment. It may also help to speed up the healing process and limit plaque formation.

How to use: Use topically by adding diluted tea tree oil to a cotton ball. Dab it on the sore spot several times per day, and continue treatment until your skin is completely healed.

Shop for therapeutic-grade tea tree oil online.

8. Witch hazel

A 1996 study found witch hazel may be effective in fighting the herpes virus and in reducing inflammation. Witch hazel is also an astringent and dries out the area, which may help with healing.

How to use: Apply witch hazel (such as Thayers Organic) directly to the skin using a moistened cotton ball. Hold it onto your skin using light pressure, and be careful not to rub. Continue treatment until your skin is fully healed.

9. Apple cider vinegar

Some people report benefits using apple cider vinegar (ACV) for fever blisters. While there’s no evidence for ACV and herpes, research shows that ACV may have anti-infective and antifungal properties.

However, it should be used cautiously on wounds given its acidic properties and potential damage to tissue. It’s not recommended for bacterial infections of the skin.

How to use: Use a cotton ball and apply diluted ACV to the affected area several times per day. You can hold it there for a few minutes at a time. Continue treatment until healed.

ACV is unsafe to consume in large amounts and can cause skin irritation.

Risks and warnings

The above remedies may not be safe for you to use if you’re pregnant or nursing. Avoid using essential oils on children or older adults. Learn how to treat cold sores in babies.

Always begin with a small amount of your chosen remedy to see how your skin reacts, and discontinue use if it irritates your skin with a prolonged burning sensation. Discontinue any home treatments if the outbreak gets worse.

Talk to your doctor if you plan on taking oral supplements. Herbal remedies and supplements can interact with any medications and cause unintended side effects.

Without treatment, a fever blister can last as long as two weeks. Unlike natural remedies, antiviral drugs are a set dose and proven to speed up the healing process, as well as lower the amount of virus present.

This table shows the general effectiveness of these drugs compared to no treatment:

TreatmentEffect
acyclovir (Xerese, Zovirax)reduces healing time by 1 to 2 days
valacyclovir (Valtrex)reduces healing time by 1 to 2 days
famciclovir (Famvir)reduces healing time by 1 to 2 days
penciclovir (Denavir)reduces healing time by 0.7 to 1 day and pain by 0.6 to 0.8 day (topical only)

Typically these medications are given in pill form. For severe or life-threatening herpes infections, people will require hospitalization and these medications will be given by vein (IV).

According to research, all approved antiviral pills, including acyclovir, valacyclovir and famciclovir, are effective at reducing days of symptoms. Topical antiviral treatments, such as penciclovir, are considered less effective.

The herpes simplex virus (HSV-1) causes fever blisters, also known as cold sores, and oral herpes. The virus can infect other parts of the body, including the genitals.

Symptoms don’t always appear right away. The virus can also lie dormant in your system and can recur at any given time. Generally, an outbreak occurs when your immune system is stressed.

Triggers

Certain triggers may reactivate the virus and cause an outbreak. These include:

  • fatigue
  • depression
  • physical or emotional stress
  • injury or trauma
  • dental procedures
  • hormone fluctuations
  • extensive sun exposure

Other health conditions that can also trigger an outbreak include:

  • whole body illness or infection
  • older age
  • individuals with organ transplants
  • pregnancy

A fever blister outbreak may be a sign of poor nutrition or of an immunity disorder. Fever blisters may accompany other medical conditions that compromise your health.

People with the following conditions have a higher risk of fever blister outbreaks:

  • weakened immune systems
  • autoimmune disease
  • cancer
  • HIV
  • severe burns
  • eczema

In more serious cases the virus can infect the hands, eyes, or the brain. If you notice blisters on other parts of your body, it’s crucial for you to visit a doctor. Other infections such as shingles can look similar and often require a different treatment course.

Schedule an appointment with your doctor if your fever blisters don’t show signs of healing after six days. You should also visit your doctor if you have:

  • severe pain
  • blisters near your eyes
  • difficulty eating or swallowing
  • a weakened immune system
  • frequent outbreaks
  • a severe outbreak
  • fever
  • pregnancy
  • worsening redness or drainage

Your doctor can also help you identify outbreak triggers or the root cause of the outbreaks. They will also determine if the outbreaks increase your risk for other complications.

Symptoms will lessen after a few days, but it will take additional time for the skin to completely heal. A normal fever blister episode heals within two weeks. During this time, there are steps you can take.

Avoid

  • touching your fever blister
  • reusing lip balm or other products that touch your mouth
  • kissing or sharing utensils, straws, and toothbrushes if you have an open sore
  • oral sexual activity if you have an open sore
  • alcohol, acidic foods, and smoking as they may irritate any sores

Once you have an outbreak, it’s possible for fever blisters to return. Usually the first outbreak is the most severe. First time outbreaks can be accompanied by fever, sore throat, swollen lymph nodes, and body aches. Future outbreaks tend to be less severe.

Currently there is no drug or vaccine for HSV-1 or HSV-2, but there are ways to help keep your outbreaks to a minimum and reduce their frequency and duration. The healthier you are, the less likely you are to have an outbreak.

Try to

  • introduce as many self-care approaches to stress reduction as you can
  • take measures to boost your immunity and stay as healthy as possible
  • always start treatment at the first sign of an outbreak
  • if needed, take daily antiviral medications to help reduce the frequency of outbreaks

A healthy diet to support your immune system may also help with outbreak prevention. A healthy diet is low in sugar, alcohol, sweetened drinks, salt, and red meat. It’s high in fresh fruits and vegetables, whole grains, fiber, nuts and beans, and lean proteins like fish, chicken, and soy.

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