What causes fever blisters?

Fever blisters, also known as cold sores or oral herpes, are a common condition affecting millions of people worldwide. These painful, fluid-filled blisters that form around the lips and mouth can be a source of embarrassment and discomfort for those who experience them. While the herpes simplex virus type 1 (HSV-1) is the main cause of this viral infection, various factors can trigger the dormant virus’s reactivation and lead to these sores.

In this article, we’ll look at the causes behind recurring fever blisters, explore the symptoms and stages of the condition, and discuss effective treatment options to help manage and prevent future outbreaks.

Understanding the herpes simplex virus

The main cause of fever blisters is the herpes simplex virus, HSV-1 strain. This highly contagious virus is estimated to infect over 90% of the adult population in the United States, though not everyone who carries the virus will experience visible symptoms. It is useful to know that HSV-2 strain is often the cause of genital herpes.

After the initial infection, the virus remains dormant in the nerve cells of the face, waiting for the right conditions to reactivate and cause another herpes infection outbreak. This reactivation can be triggered by a variety of factors, including:

Hormonal changes

Fluctuations in hormone levels, such as those experienced during menstruation or pregnancy, can disrupt the delicate balance of the immune system and increase the risk of a fever blister outbreak.

Stress and fatigue

Physical or emotional stress, as well as prolonged periods of tiredness, can weaken the body’s defences, making an individual more susceptible to the reactivation of the herpes virus.

Close contact

Close skin contact with an infected person particularly through kissing can cause fever blisters. Additionally sharing utensils, straws, towels or lip balm with someone who has a cold sore can increase your risk.

Exposure to sunlight

Ultraviolet (UV) radiation from the sun can damage the skin and trigger the reactivation of the virus, leading to the development of fever blisters.

Illness and fever

Viral or bacterial infections that cause fever can also stimulate the herpes virus, leading to the appearance of fever blisters.

Trauma or injury

Damage to the skin, such as through biting, chewing, or even dental work, can provide an entry point for the virus and lead to fever blisters.

Understanding these common triggers is crucial for individuals who experience recurrent cold sore outbreaks, as they can take steps to minimise their exposure and reduce the frequency of outbreaks.

Symptoms and stages of fever blisters

The appearance and progression of fever blisters typically follow a predictable pattern, with several distinct stages:

Tingling and itching

The initial stage of a fever blister outbreak is often characterised by a tingling, burning, or itching sensation around the lips or mouth. This early warning sign typically occurs 12 to 24 hours before the visible appearance of the blisters.

Blister formation

As the virus reactivates and begins to replicate, small blisters filled with fluid start to form on the lips, around the mouth, or even on the cheeks or nose. These painful blisters may cluster together, creating a larger, more unsightly sore.

Oozing and crusting

Over the next few days, the blisters will typically rupture, releasing a clear or slightly yellow fluid and creating an open sore. This “weeping” phase can be particularly uncomfortable and increases the risk of the virus spreading to other individuals through contact.

Healing and scabbing

As the blisters begin to heal, a crusty scab will form over the affected area. This scab may crack or bleed as it dries out, but the skin will eventually return to its normal appearance within one to two weeks.

It’s important to note that the severity and duration of a fever blister outbreak can vary from person to person, with some individuals experiencing more frequent or severe episodes than others. Understanding the typical progression of the condition can help individuals better manage their symptoms and seek appropriate treatment when necessary.

Distinguishing fever blisters from canker sores

While fever blisters and canker sores (also called aphthous ulcers) may appear similar at first glance, they are distinct conditions with different causes and characteristics. Correctly identifying the type of oral sore is crucial for determining the appropriate course of treatment.

Location

The main distinguishing factor between fever blisters and canker sores is their location. Fever blisters typically appear on the outside of the mouth, around the lips, while canker sores are found exclusively on the inside of the mouth, such as on the gums, cheeks, or tongue.

Appearance

Fever blisters are characterised by a cluster of small, fluid-filled blisters, while canker sores present as a single, round, white or yellow sore with a red border.

Cause

Fever blisters are caused by the herpes simplex virus, while the exact cause of canker sores is unknown, though they may be triggered by factors such as injury, stress, or nutritional deficiencies.

Contagiousness

Fever blisters are highly contagious, as the herpes virus can be transmitted through direct contact or sharing personal items. Canker sores, on the other hand, are not contagious.

Understanding the key differences between these two types of oral sores can help individuals seek the appropriate medical treatment and take the necessary precautions to prevent the spread of the herpes virus.

Complications

While fever blisters are generally not a serious condition for most individuals, they can lead to complications in certain cases, particularly for those with weakened immune systems or other underlying health conditions.

Eye infections

The herpes simplex virus responsible for fever blisters can potentially spread to the eyes, causing a condition known as herpetic keratitis. This eye infection can lead to corneal scarring and, in severe cases, even vision loss if left untreated.

Genital herpes

In rare instances, the HSV-1 virus that causes fever blisters can be transmitted to the genital area through oral-genital contact, leading to the development of genital herpes. This can happen after having oral sex with someone who has genital herpes, which is usually caused by herpes simplex virus type 2 (HSV-2). This can be a significant source of concern, as genital herpes is a sexually transmitted infection.

Eczema herpeticum

For individuals with pre-existing skin conditions, such as eczema, the herpes virus can spread rapidly across the body, leading to a potentially life-threatening infection known as eczema herpeticum. This condition requires immediate medical attention and treatment.

Outbreaks in newborns and immunocompromised individuals

Newborns and individuals with HIV/AIDS or undergoing cancer treatment who have a weak immune system are at a higher risk of developing severe, potentially life-threatening complications from fever blister outbreaks. These individuals should seek prompt medical care at the first sign of symptoms.

Diagnosis

Diagnosing fever blisters is typically a straightforward process, as the characteristic appearance of the blisters is often enough for a healthcare provider to make a diagnosis. In some cases, a swab of the affected area may be taken to confirm the presence of the herpes simplex virus.

Treatment options

In healthy people, cold sores generally clear up on their own in one to two weeks. There are several treatment options available to help manage the symptoms and shorten the length of an outbreak:

Antiviral Medications

Prescription antiviral creams or oral medications, such as acyclovir, valacyclovir, or famciclovir, can be effective in reducing the severity and duration of fever blister outbreaks. Antiviral medicines work by inhibiting the replication of the virus, helping to speed up the healing time.

Over-the-counter remedies

For milder cases, over-the-counter topical creams or ointments containing ingredients like benzocaine or docosanol can provide relief from the pain and discomfort associated with fever blisters. These products can help soothe the affected area and promote healing. You can also take acetaminophen/paracetamol or ibuprofen orally to ease your discomfort.

Home remedies

In addition to medication, several home remedies may help alleviate the symptoms of fever blisters, such as applying a cool compress to the affected area, avoiding acidic or spicy foods, and keeping the lips moisturised with a lip balm containing sunscreen.

It’s important to note that while these treatments can help manage the symptoms of fever blisters, they cannot cure the underlying viral infection. The herpes simplex virus will remain dormant in the body, and individuals may continue to experience recurrent outbreaks in the future.

Prevention

For individuals who experience frequent fever blister outbreaks, taking proactive steps to prevent future episodes can be crucial in managing the condition and minimising its impact on their daily lives.

Identifying and avoiding triggers

Understanding the specific triggers that can reactivate the herpes virus and lead to the development of fever blisters is the first step in prevention. By identifying and avoiding these triggers, such as excessive sun exposure, stress, or hormonal changes, individuals can reduce the frequency and severity of their outbreaks.

Maintaining a healthy immune system

Keeping the immune system strong and resilient is essential in managing the herpes virus and preventing future fever blister outbreaks. This can be achieved through a balanced diet, regular exercise, and adequate sleep, as well as by managing stress levels and any underlying health conditions.

Practicing good hygiene

Proper hygiene practices, such as washing hands frequently, avoiding sharing personal items and eating utensils, and keeping the affected area clean and dry, can help prevent the spread of the herpes virus and reduce the risk of transmission to others.

Seeking medical advice

For individuals who experience frequent or severe fever blister outbreaks, consulting with a healthcare provider may be beneficial. They can guide the most effective treatment options, as well as recommend preventative measures tailored to the individual’s specific needs.

By taking a proactive and comprehensive approach to managing fever blisters, individuals can minimise the impact of this condition on their overall health and well-being.

Conclusion

Fever blisters is a common and often frustrating viral condition, caused by the herpes simplex virus. It can be triggered by a variety of factors, including hormonal changes, stress, sun exposure, illness, and physical trauma. Understanding the underlying causes, symptoms, and stages of fever blisters is crucial for individuals to effectively manage their outbreaks and minimise the impact on their overall health and well-being.

Sources

• Cold sore – Symptoms and causes – Mayo Clinic
• Cold Sore: Causes, Treatment & Prevention
• Fever Blisters & Canker Sores – National Institute of Dental and Craniofacial Research