How Effective Is Red Light Therapy for Cold Sores?

Red light therapy is a type of non-invasive therapy that is gaining popularity for its numerous applications. It uses red and near-infrared wavelengths of light (600–1,100 nm) for potential beauty and health benefits, ranging from skin rejuvenation to wound healing.

Here, we will provide an overview of the various clinical studies evaluating the utility of red light therapy in the treatment of cold sores, along with the typical length and frequency of sessions. We will also explore the devices and the attributes one should look for. Additionally, we will outline the guidelines and restrictions.

Understanding cold sores

A cold sore is the appearance of a blister typically around the lips, yet it may occur on other areas of the face as well. In scientific language, it is referred to as herpes labialis. It is caused by the herpes simplex virus type 1 (HSV-1) infection. A cold sore appears as a red, swollen blister filled with fluid. It may also occur as a group of blisters. The infection usually spreads through skin-to-skin contact.

The symptoms begin with tingling, itching, and a burning sensation, leading to painful blisters, which ooze a clear to yellowish fluid. Then, the sore gradually dries out to form a crust that finally falls off. The course takes between five to 19 days. The initial or primary infection usually lasts longer and is accompanied by other symptoms, such as fever and swelling of lymph nodes.

People commonly experience a recurrence since the virus stays in the body. Outbreaks are often triggered by stress, hormonal changes, fever, or sunburn. There are medicines available to treat cold sores and reduce the healing time, but the infection cannot be cured.

Does red light therapy help with cold sores?

Very few studies have evaluated the effectiveness of red light therapy for treating cold sores. The limited evidence suggests that red light therapy can shorten the healing time and modestly reduce the recurrence rate.

A study by a research group in Brazil monitored 158 patients with recurrent herpes labialis over two years following a six-month red light therapy regimen. The therapy involved 15 sessions using the wavelengths of 660 nm and 808 nm, i.e., red and near-infrared light, respectively. The researchers reported significant improvement in both the recurrence rate and severity of symptoms.

In another study, the effects of near-infrared laser (at a wavelength of 870 nm) in the treatment of recurrent cold sores was compared with acyclovir cream. The results showed significantly decreased healing time and reduced pain intensity in the low-level laser group, as compared to the acyclovir group.

The above findings contrast with the most recent randomized clinical trial results, in which patients received either laser irradiation with 650 nm wavelength of red light for two minutes or acyclovir cream and a passive laser for five days. While red light therapy did lead to a faster reduction of pain than acyclovir cream after second application of laser, there was no difference in the healing time between the two groups.

It should be noted that the overall quality of evidence is insufficient to confirm the effectiveness of red light therapy as an intervention for cold sores.

Red light therapy works through photobiomodulation. While the exact mechanism is not fully understood, it is believed that red light therapy triggers several beneficial processes. These include enhancing the natural immune response, boosting lymphocyte activity, increasing levels of key cytokines, and improving blood flow and oxygenation. Together, these effects may potentially help block viral replication and accelerate the repair process. However, more research is needed to examine the proposed benefits further.

How to use red light therapy for cold sores

For cold sores, red light therapy is typically administered using small hand-held devices. Considering the high incidence and contagious nature of cold sores, owning an at-home red light therapy device can be a practical option. Alternatively, professional red light therapy is also available at some dental offices. The latter option should always be prioritized over the at-home red light therapy.

Here is a list of typical directions that are followed across the majority of clinical studies while administering red light therapy for the management of cold sores.

1. Start the therapy soon after the onset of cold sore symptoms. Initiating red light exposure within the first few hours maximizes the effect.
2. According to some studies, red light laser irradiation can be used at the cold sore site as well as at the C2–C3 vertebrae site. The researchers suggest using a shorter irradiation duration while the cold sore is in the vesicle stage and a longer duration for the crust stage. A typical regimen dictates daily irradiation sessions through the course of outbreak.
3. Methylene blue may also be used in combination with red light therapy to enhance the benefit. This is referred to as photodynamic therapy, and its use is limited to clinical settings.
4. There are also reports where red light therapy is used in conjunction with antiviral creams or gels for better results.

There is significant variation in reports describing the red light therapy regimen for cold sores, with parameters like frequency and wavelength not yet standardized. Most studies suggest daily sessions lasting two to three minutes throughout the outbreak. It's important to follow the recommended usage guidelines or consult a red light therapy expert to develop an appropriate therapy plan.

If you have ever used red light therapy to treat cold sores, please share your experience in the comments.

How to choose a red light therapy device for cold sores

To ensure safety and effectiveness, it is necessary to choose an FDA-cleared device. Several red light therapy devices are available in the market, but most of them lack FDA approval or clinical validation. Ease of operation, price, therapy parameters, and approval by some regulatory bodies are the criteria for choosing the device.

There is a wide range of red light therapy devices, such as large panels, face masks, wrap belts, and handheld wands. However, it is advisable to choose an FDA-cleared device specifically approved for treating cold sores. The safety of many commercial red light therapy devices is questionable, so it's important to consult with your healthcare provider before making a purchase to ensure the device is both safe and suitable for your needs.

Potential risks and side effects

Red light therapy treatment is non-invasive and generally considered a safe alternative treatment. Systematic reviews of clinical studies indicate no significant negative effects when using red light therapy for managing cold sores. Typically, the short exposure durations required for cold sore treatment do not result in adverse reactions.

However, like any therapy, red light therapy may have side effects. Here, we list a few conditions in which there is some risk associated with exposure to red light:

• Irradiation sessions may worsen photosensitivity symptoms.
• The safety of red light therapy hasn't been checked on cancerous tissues.
• Light exposure may trigger seizures in people with epilepsy.
• Therapy may cause rashes or sunburns.
• Red light therapy should be avoided in the presence of active infections.
• Red light therapy should also be avoided if using any medications that can increase photosensitivity.
• The safety of red light therapy hasn't been evaluated in those pregnant, breastfeeding, or below 18.

Established treatments for cold sores

Several antiviral medications, including acyclovir, penciclovir, and famciclovir, are commonly used to treat cold sores. These can be administered either orally or as topical gels and creams.

For symptomatic relief, creams like docosanol and pain-relieving or anesthetic creams are often used. Since sunburn can trigger cold sores, patients may also use sunscreens to help prevent outbreaks.

However, the use of antiviral drugs may lead to the emergence of drug-resistant strains, and oral administration can result in systemic toxicity. Therefore, there is a pressing need to explore and develop new therapeutic approaches. The molecules of the immune system, interferons, and immunoglobulins are currently being investigated as potential treatment options for cold sores.

Bottom line

Red light therapy is considered a safe and cost-effective option for managing cold sores. However, research data on its effectiveness is limited and not yet sufficient to confirm its benefits fully. Despite this, some limited evidence suggests that red light therapy may help with pain relief, faster wound healing, and reducing the frequency of cold sores. It's essential to use FDA-cleared devices and follow your healthcare provider's guidance on the therapy plan. Further research is needed to establish its efficacy more conclusively.