In this article:
Fever blisters, commonly known as cold sores, refer to a cluster of white blisters forming around the lips. These are caused by infection with the herpes simplex virus and thus also known as herpes labialis. (1)
Most cases of fever blisters resolve on their own within 10–14 days. (2) Medical diagnosis and treatment, however, are suggested to prevent recurrence of the disease.
This article discusses the treatment and complications associated with fever blisters.
Causes of Fever Blisters
Fever blisters are caused by the herpes simplex virus. While herpes simplex virus type 1 (HSV-1) is mainly responsible for these outbreaks, fever blisters can also be caused by herpes simplex virus type 2 (HSV-2). Once the herpes simplex virus infects a person, the virus lies dormant in the trigeminal nerve ganglion for years.
Due to local or systemic stimuli and an alteration in the immune response, the virus reactivates itself to cause an infection. The infection can occur anywhere on the body, and when it occurs on the lips, it is called fever blisters or cold sores.
It is possible that you may have been infected with the virus in childhood and get fever blisters at a later age.
Symptoms of Fever Blisters
Fever blisters initially present as tingling, burning, or itching sensation, generally on or around the lips. Within 2 days of onset, you may notice the development of a cluster of red blisters on the area, which may be painful and irritating.
With time, the blisters may turn white due to pus formation and cause swelling in the surrounding skin. Once the blisters mature, they burst and dry out to form a flaky slab.
Treatment for Fever Blisters
It is vital to treat fever blisters at the earliest using antiviral medications to prevent recurrence or complications. The treatment for fever blisters depends on various factors and can include the following:
- Oral antivirals: These include famciclovir, acyclovir, and valacyclovir, generally used for mild to moderate blisters. Oral antivirals may also be used for chronic daily suppressive therapy. (3)
- Topical analgesics: Lidocaine cream is useful in managing the pain associated with fever blisters.
- Oral analgesics: In some cases, the doctor may prescribe ibuprofen or paracetamol to control the pain and inflammation.
- Buccal adhesive tablet: This is used for the episodic treatment of fever blisters.
- Sage-rhubarb ointments: Studies have shown that sage and rhubarb are as efficacious as acyclovir cream for the treatment of fever blisters. (4)(5)
- Topical creams: You may be prescribed zinc oxide or sulfate ointments. In addition, penciclovir cream may be given to those with a weak immune system to prevent recurrence of the sores.
- Steroid cream: Topical creams such as cortisone can be given to control the swelling.
- Light therapy: This is used for recurrent cases of fever blisters that cannot be controlled by medications. You may be suggested to undergo photodynamic therapy, low-level laser treatment, or high-level light treatment to help increase the interval between episodes and also control the pain. Laser therapy is highly useful for immunocompromised and older patients. (6)(7)
Diagnosing Fever Blisters
In most cases, the doctor can easily diagnose fever blisters based on their characteristic symptoms, but further evaluation may be needed if the infection occurs anywhere other than around the mouth. In such cases, a fluid sample from the blisters will be lab tested for the presence of the suspected herpes virus.
Recurrence of Fever Blisters
The herpes simplex virus, after infecting the nerve cells, remains dormant in the ganglion for the person’s lifetime. The sores only occur when the virus activates and moves to the mouth region, causing sores.
Risk Factors for Fever Blisters
Factors that can reactivate the herpes simplex virus and lead to an outbreak of fever blisters include:
- Medical conditions such as atopic dermatitis
- Weakened immune system
- Physical or emotional stress
- Certain drugs
- Physical injury or trauma
- Excessive or unprotected sun exposure
- Dental or other oral surgery
Complications Associated With Fever Blisters
Fever blisters, if left untreated, can lead to the following complications:
- Herpes whitlow if the virus spreads to the fingers
- Obstruction or loss of vision if the virus reaches the eyes and causes infection
- Genital infections
- Throat infections
- Ulceration that fails to subside
- High fever and seizures in infants below the age of 6 months
When to See a Doctor
It is best to consult your doctor anytime you suspect you have fever blisters to get a confirmed diagnosis and timely treatment and to prevent complications.
In addition, consult your doctor if you have or develop any of the following complications along with fever blisters:
- Atopic dermatitis
- Compromised immune system due to HIV, AIDS, chemotherapy, use of steroids or antirejection drugs, or any other disease/condition
- Pain in the sores
- Spread of sores to other body parts such as hands, eyes, or genitalia
- Sudden development and frequent recurrence of sores
- Prolonged sores that don’t heal after 2 weeks
- Painful, swollen gums and sores in the mouth
Fever blisters, or cold sores, are caused by an infection of the facial nerves with human herpes simplex viral strains. The virus remains dormant in your body throughout your lifetime, but you can seek medical treatment and follow self-care measures to prevent outbreaks.
If you do develop fever blisters, make sure to consult your doctor and get appropriate treatment, especially if the problem is recurrent. In addition to the prescribed antivirals, you can use different at-home remedies to facilitate recovery and prevent recurrence.