ANSWER:
I get Fever blisters too and have tried several of the home remedies listed at the bottom of this answer. I’ve also tried Abrevia, and found that it doesn’t help as much as it claims to. The relief that I have found most helpful are Zinc cream applied several times a day and Oregano oil applied several times a day.
I hope this helps, but you should do what the home remedies say about buying a new tooth brush. The fever blister will go away on its own in about 2 weeks from the time it appeared. In the mean time its is a completed hassle to deal with, especially if you get them in the corner of your lip like I do. Makes it hard to open your mouth to eat. You need to be cautious not to pick at the scab that will form or to accidentally cause it to split by opening your mouth too wide.

Today Oil of Oregano is known as a cure for, and it’s ability to stop a cold sore/fever blister dead in it’s tracks.
Using a thin coating of Oil of Oregano on the infected area at first signs of a cold sore will stop the sore from ever developing in to a full blown fever blister.
To help kill the herpes virus living inside of your body take one drop of Oil of Oregano internally for one week, after the second week take two drops internally. You can work your way up to 3 drops a day to help insure a healthy strong immune system.
Herpes Simplex on the Lips Cold Sores (Fever Blisters)

Causes

Cold sores are usually caused by the herpes simplex 1 virus, but sometimes can be caused by the herpes 2 virus that causes genital herpes . The two viruses are related, but different. The virus invades the skin, then lies dormant for weeks or months before causing inflammation and blistering.

In most cases, people contract the virus as infants or young children. The first episode of illness with herpes simplex 1 virus causes a systemic illness. The virus then lies dormant until it is reactivated. Once reactivated, it results in painful cold sores, usually located at the border of the colored part of the lip.

The virus can be spread by:

* Contact with the fluid from a cold sore of another person
* Contact with the eating utensils, razors, towels, or other personal items of a person with active cold sores
* Sharing food or drink with a person with active cold sores
* Contact with the saliva of a person who has the herpes simplex virus

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. Infection with the virus that causes cold sores is so common that everyone is considered at risk.

Once the herpes simplex 1 virus is present in the body, the following risk factors can trigger cold sores to form:

* Transplantation
* Malnutrition
* Infection, fever, cold, or other illness
* Exposure to sun
* Physical or emotional stress
* Certain foods or drugs
* Weakened immune system
* Menstruation
* Eczema
* Physical injury or trauma
* Dental surgery
* Excessive exercise

Cold sores often form without an identifiable trigger.
Symptoms

The first episode of herpes simplex 1 infection may result in 3-14 days of:

* Swollen, sore throat
* Mouth sores
* Fever
* Decreased energy
* Aches and pains
* Difficulty eating
* Swollen glands in the neck
* Headache

After this initial illness has passed, the virus lies dormant until reactivated. In the day just prior to the virus reappearing as a cold sore, you may notice some itching, burning, or pain in the area where the cold sore will appear.

Symptoms of cold sores on the lips, mouth, or skin include:

* Small, painful, fluid-filled, red-rimmed blisters
* Pain, tingling, or itching for a day or two before the blister appears
* After a few days, drying of the blister, which then forms a yellow crust and shallow ulcers

Diagnosis

The doctor will ask about your symptoms and medical history, and examine the blisters. Usually, the doctor can easily diagnose a cold sore by looking at it. Cold sores have a relatively classic appearance. In rare cases, the doctor may need to take a piece of a blister to analyze it or take a blood sample for testing.
Treatment

Cold sores will usually heal within 7-20 days. Treatments for blisters on the lips, mouth, or skin include:

* Putting ice on blisters to lessen pain and promote healing
* Not rubbing or scratching blisters
* Nonprescription pain relief drugs to lessen pain and discomfort
* Nonprescription cold sore/fever blister cremes and ointments to lessen pain
* Antibiotic drugs if the blister becomes infected by bacteria
* Antiviral creme or ointment if you suffer from frequent herpes simplex 1 virus outbreaks
* Oral antiviral medications, such as Zovirax (acyclovir), Valacyclovir (Valtrex), Famcidovir ( Famvir), or Denavir (penciclovir), may be given the moment you feel a cold sore coming on. These medications can decrease discomfort and help cold sores go away more quickly.

Smear yourself with sunscreen. Sunlight triggers one of every four cases of cold sores. New research shows that applying an SPF (sun protection factor) 15 sunscreen to your lips and other susceptible areas before venturing outdoors may be all you need to prevent recurring cases. In studies, researchers at the National Institutes of Health in Bethesda, Maryland, and the University of California Hospital in Los Angeles found that patients prone to cold sores who applied sunscreen prior to ultraviolet light exposure got total protection. Those who didn’t apply sunscreen got their usual number of new outbreaks.

Replace your toothbrush. Your trusty toothbrush can harbor the herpes virus for days, reinfecting you again and again after the cold sore first heals. So toss your toothbrush as soon as you notice the beginning of a blister, advises Richard T. Glass, D.D.S., Ph.D., chairman of the Department of Oral Pathology at the Colleges of Dentistry and Medicine at the University of Oklahoma in Oklahoma City. Use the new toothbrush until the sore has healed completely, then replace that one.

Try milk. A compress of whole milk placed directly on the cold sore can ease pain and speed the healing process, says Jerome Z. Litt, M.D., assistant clinical professor of dermatology at Case Western Reserve University School of Medicine in Cleveland. Allow the milk to sit at room temperature for 10 to 15 minutes before placing the compress on your skin. Be sure to rinse your skin afterward, because the milk can become sour smelling. Note: Whole milk, with its extra protein, works–other kinds don’t have the same healing effect.

Watch what you eat. The herpes simplex virus needs the amino acid arginine for its metabolism. So if you’re prone to cold sores, limit your intake of arginine-rich foods such as chocolate, cola, peas, cereals, peanuts, gelatin, cashews and beer, advises D’Anne Kleinsmith, M.D., a cosmetic dermatologist at William Beaumont Hospital near Detroit. Of course, during an outbreak, eliminate these foods altogether.

Lick it with lysine. People who get more than three cold sores a year are advised to supplement their diets with between 2,000 and 3,000 milligrams daily of lysine, an amino acid that counter-acts arginine, says Mark A. McCune, M.D., chief of dermatology at Humana Hospital in Overland Park, Kansas. Lysine is sold at most health food stores and some drugstores.

Try the direct method. Applying ice or an over-the-counter product containing zinc oxide directly to the cold sore can speed healing. Gauze soaked in Domeboro astringent solution and applied to the cold sore helps dry it up. “Witch hazel also works by drying out the blister, but it hurts and may not be quite as effective,” says Dr. Kleinsmith.