What Causes Cold Sores? Complete Guide

Cold sores are caused by the herpes simplex virus type 1 (HSV-1), affecting up to 70% of the UK population. Understanding what triggers cold sore outbreaks can help you manage symptoms more effectively. While the virus remains dormant in your system after initial infection, certain factors can reactivate it, leading to painful blisters around the mouth and lips.

  • Initial infection occurs through direct contact with infected saliva or lesions
  • Stress, illness, and weakened immunity can trigger outbreaks
  • Sun exposure and hormonal changes are common activation factors
  • Antiviral treatments like aciclovir can reduce severity and duration
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Available Treatments

Choose from a wide range of clinically-proven, safe, and effective treatments for Cold Sore.

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Aciclovir Tablets

From £12.99

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Aciclovir 5% Cream

From £8.99

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Valaciclovir

From £18.99

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Valtrex

From £34.99

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Understanding HSV-1 Transmission and Triggers

Primary Infection: How HSV-1 Enters Your System

Cold sores result from infection with herpes simplex virus type 1 (HSV-1). The initial infection typically occurs during childhood through direct contact with infected saliva, such as sharing utensils, kissing, or touching contaminated surfaces. Many people experience their first outbreak within 2-20 days of exposure, though some may never develop visible symptoms despite carrying the virus.

Once HSV-1 enters your body, it travels along nerve pathways and remains dormant in nerve cells near your spine. This dormant state explains why cold sores can reappear throughout your lifetime, even years after the initial infection.

Common Cold Sore Triggers

Several factors can reactivate the dormant HSV-1 virus, leading to cold sore outbreaks. Stress remains one of the most significant triggers, as elevated cortisol levels can suppress your immune system's ability to keep the virus dormant. Physical stress from illness, surgery, or injury can similarly trigger outbreaks.

Hormonal fluctuations during menstruation, pregnancy, or menopause frequently cause cold sore recurrences in women. Sun exposure and extreme weather conditions can also activate the virus, which is why cold sores often appear after holidays or outdoor activities.

Risk Factors and Prevention Strategies

Certain individuals face higher risks for cold sore outbreaks. Those with compromised immune systems, including people with HIV, cancer patients undergoing chemotherapy, or individuals taking immunosuppressive medications, may experience more frequent or severe outbreaks.

Age also plays a role, as children and elderly individuals typically have less robust immune responses. Additionally, people with eczema or other skin conditions around the mouth area may be more susceptible to HSV-1 infection and recurrent outbreaks.

Treatment Options Available

When cold sore symptoms begin, antiviral medications can significantly reduce outbreak duration and severity. Aciclovir tablets, available through EverydayMeds, work by preventing viral replication when taken at the first sign of symptoms. The standard dose of aciclovir 400mg is typically taken five times daily for five days, though treatment is most effective when started within 24-48 hours of symptom onset.

Topical treatments like aciclovir 5% cream can provide localised relief and may help prevent the spread of infection to other areas. For individuals experiencing frequent outbreaks (six or more per year), suppressive therapy with daily antiviral medication may be recommended.

Alternative antiviral options include valaciclovir, which offers convenient twice-daily dosing and may be preferred for some patients. EverydayMeds provides access to various antiviral treatments following online consultation with qualified healthcare professionals.

Managing Outbreaks and Preventing Transmission

During active outbreaks, cold sores remain highly contagious until completely healed. Avoid direct contact with the affected area and maintain strict hygiene practices, including frequent handwashing and avoiding sharing personal items like towels, utensils, or lip products.

Pain management during outbreaks may include over-the-counter analgesics and cool compresses applied to affected areas. Keeping the area clean and dry promotes healing, while avoiding picking or touching blisters prevents secondary bacterial infections and scarring.

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