Cold sores, caused by Herpes simplex viruses are a common and annoying problem. Antibody studies suggest that, worldwide, as many as nine out of ten people are infected.

Cold sores are highly infectious

Most people with lip cold sores encounter the virus during the first 18 months of life as a result of being kissed by an infected adult. The initial, or primary, infection may pass unnoticed or is often dismissed as ‘teething’, although widespread, excruciatingly painful sores can develop all over the inside of the mouth.

Cold sores are teeming with viral particles and are highly infectious from the time they first appear until they are fully healed. If you have cold sore symptoms, it is important to avoid kissing someone, or having intimate contact until the cold sore is fully healed, or you may pass on the infection.

Cold sore recurrences

During the first attack, hundreds of viral particles travel up nerve endings and lie dormant in a swelling (ganglion) near the nerve root. Here, the Herpes simplex produce short strands of genetic material known as microRNAs that ‘tell’ the virus to stay inactive. When conditions are right, however, the virus stops making microRNA and reactivates to cause a recurrent cold sore.

During reactivation, a few Herpes viruses travel back down the nerve. During this phase, many people notice a characteristic tingling, burning, itching or lightning pains which are known as a prodrome. These symptoms last for 12 to 24 hours and usually herald the onset of one or more blisters.

The blisters develop quickly once viral particles reach the skin, spreading from cell to cell and hi-jacking their machinery to make more viral proteins and viral genes. This kills the cells, which burst to release new Herpes simplex viruses. The burst cells form fluid-filled vesicles which join together to create a shallow ulcer which is particularly painful as the underlying nerve endings are exposed.

Eventually, the ulcers crust and scab over to heal within 10 – 14 days and the cycle starts over again as new viruses travel up to the nerve ganglion to lie dormant.

It’s estimated that only one in three people who carry the Herpes simplex virus experience recurrent symptoms. The Herpes simplex virus is sometimes detectable in mouth swabs from people who do not have symptoms, however. This asymptomatic shedding of low numbers of virus can still pass on the infection to those who are not immune. It’s not known how common this phenomenon is, but I have seen many people who developed Herpes for the first time ‘out of the blue’ even though their regular partner did not have any symptoms.

Cold sore triggers

Anything that reduces your immunity can trigger a recurrent cold sore. The most common trigger is having another viral infection such as a common cold (hence the name, cold sores), but frosty weather and prolonged periods of stress can also reactivate the cold sore virus. My worst cold sore was a horrible, painful blister that appeared the weekend after I’d completed my medical finals which involved two exams a day for two weeks. Cold sore recurrences are also triggered by exposure to ultraviolet light, such as when skiing, during a beach holiday or using a sun bed. Sometimes, applying a lip total sun block is enough to protect against a recurrence on holiday. I also recommend using licorice balm (see below) and taking vitamin C tablets.

The best cold sore treatments

A range of different treatments is available in pharmacies to treat cold sores. The simplest contain soothing balms, local anaesthetics or antiseptics, or simply provide a protective cover. The cold sore treatments that I have found most effective in clinical practice are taking vitamin C tablets plus using a licorice balm, but I’ve also reviewed other treatments with some evidence for effectiveness, such as aciclovir cream, silica gel, medicinal honey and Echinacea.

NB This review covers the treatment of Herpes lip cold sores. If you have genital herpes, it is important to seek medical advice and treatments from a doctor or sexual health clinic.

Licorice for cold sores

Licorice (also spelled liquorice) root extracts are one of the most effective natural treatments for cold sores, a use that was even recognised in ancient Chinese, Indian and Greek medicine.

Licorice extracts contain substances known as triterpenoids (eg glycyrrhizic acid, glycyrrhizin, glycyrrhetinic acid) which specifically block the multiplication of the Herpes cold sore and other viruses. This inactivation of Herpes viruses is irreversible but does not harm the infected cells themselves.

Licorice balm can reduce the severity and duration of outbreaks for over 73% of those tested, with outbreaks lasting healing twice as quickly as normal.

Research published in the Journal of Clinical Investigation suggests that licorice can also kill latent Herpes viruses. Pain resolves quickly, usually within 24 hours, and ulcers heal within 3 days.

Applying licorice balm to the lips regularly can, in some cases, eradicate the virus lying dormant between outbreaks. I have personally found liquorice cold sore treatments more effective than those containing aciclovir.

Liquorice extracts also have anti-inflammatory pain killing actions to sooth symptoms as it hastens healing.

Licorice balm tastes delicious and when applied as soon as you feel the first symptoms will usually stop a cold sore in its tracks. Apply it regularly, as often as needed – try not to lick it off.

Vitamin C for cold sores

Vitamin C has powerful antiviral actions and has even been used in hospitals as an infusion to treat persistent viral infections that have not responded to antiviral drugs. Viral particles cannot replicate inside cells when vitamin C (ascorbic acid) levels are high. Vitamin C almost completely inhibits the formation of new infectious viruses by preventing the assembly of viral particles.

Applying a vitamin C solution (on a cotton pad pressed against the cold sore) for two minutes, on three occasions, half an hour apart, for just one day, was found to significantly improve subsequent cold sore symptoms, with significant numbers of sores not worsening any further after treatment. According to nurse records, the persistence of scabs was 3.4 days in those receiving the vitamin C treatment, compared with 5.9 days with placebo. Swabs also yielded Herpes virus less frequently after vitamin C treatment.

Vitamin C tablets taken by mouth to boost tissue levels are also effective. When twenty cold sore outbreaks were treated by taking  200 mg vitamin C plus bioflavonoids, three times a day, blisters were stopped in their tracks in three out of four people. The average time from onset to complete healing was significantly reduced  to 4.3 days in those taking vitamin C compared with 9.7 days in those receiving placebo.

Aciclovir cream for cold sores

If you speak to a pharmacist about cold sore treatments, chances are they will advise using aciclovir cream (eg Zovirax) or a stronger version containing penciclovir (Fenistil).

Aciclovir is an antiviral drug which, in the laboratory, is highly active against Herpes simplex viruses. When it enters a herpes-infected cell, it is activated by a viral enzyme (thymidine kinase) to produce aciclovir triphosphate. This inhibits another herpes enzyme to prevent the production of viral DNA. In theory, this should work really well, but clinical trials of aciclovir cold sore creams have produced disappointing results.

In two large clinical studies involving 1,385 people with recurrent herpes cold sores, aciclovir cream was not that much more effective than placebo cream in treating an active cold sore. Time from start of treatment to healing was 4.6 days using aciclovir cream and 5.0 days using the plain cream. Although this was a statistically significant improvement (p<0.001) aciclovir cream only reduced healing time by half a day. Duration of pan was 3.0 days with aciclovir cream, and 3.4 days with plain cream.

When it comes to prevention, however, using aciclovir cream is more effective. Applying aciclovir cream was found to reduce the chance of experiencing a recurrent lip sore among 191 skiers. All those taking part had experienced more than three episodes of sun-induced herpes cold sores during the previous year. Those using preventive aciclovir cream during their skiing holiday developed significantly fewer Herpes cold sores than those using a placebo cream (21% versus 40%). The researchers suggested that applying aciclovir cream is an effective preventive step for those whose cold sores are activated by exposure to the sun.

In clinical studies, penciclovir cream (Fenistil Cold Sore cream) healed cold sores 30% faster than placebo (up to one day earlier), while pain and infectiousness resolved up to one day faster than with placebo.

In the US, the main over-the-counter drug treatment for herpes cold sores is docosanol. Clinical trials comparing docosanol with placebo in 737 people who applied treatment five times a day, at the first sign of symptoms, found that docosanol shortened the duration of symptoms by just 18 hours compared with placebo. Attacks stopped progressing in 40% of those using docosanol compared with 34% using placebo cream. These treatments are not as effective as licorice balm.

Silica gel for cold sores

Silica gel is at least as effective as acyclovir cream in treating recurrent herpes cold sores. This was tested in 74 people with recurrent cold sores who applied either silica gel or aciclovir cream, starting within 24 hours of the first symptoms. There were no significant differences between silica gel and aciclovir cream response, but silica gel appeared to relieve all symptoms earlier than aciclovir cream.

Medicinal honey for cold sores

Honey has antiviral and anti-inflammatory actions. A small indicative study involving 16 adults with recurrent herpes cold sores found that applying a multiflora honey was more effective than aciclovir cream for treating both oral and genital recurrent herpes cold sores. Average healing time for Herpes cold sores was 3 days shorter when applying honey compared with aciclovir (2.6 days versus 5.9 days. It is important to apply a medicinal grade honey, however, to ensure sterility.

A large clinical trial is currently underway, which will compare the effectiveness of 90% kanuka honey and aciclovir cream in 950 people with Herpes simplex cold sores in New Zealand.

Compeed cold sore patches  

Compeed cold sore patches cover a cold sore with a thin, hydrocolloid cover which protects it from the elements, reduces pain, improves appearance and may slow viral replication. In a study involving 351 people with a recurrent Herpes simplex cold sore, half used Compeed cold sore patches as treatment, and half used aciclovir cream. Both treatments were declared ‘highly effective’ and there were no significant differences in healing times. As well as providing wound protection, however, the patch hid the sore to reduce social embarrassment. You can even apply lipstick over it!

Echinacea for cold sores

Echinacea, or purple coneflower, is a traditional remedy used by native Americans to treat infections, including cold sores. Echinacea increases the proliferation and activity of immune cells responsible for fighting infections and is widely used to reduce herpes recurrences. In cell cultures, Echinacea pressed juice was found to reduce herpes virus activity by more than 99%.

I recommend using the A.Vogel Echinacea product which is made from fresh juice. It is preserved in an alcohol tincture which you add to water or fresh juice to drink. While you can apply the tincture direct to an early lip blister, it will sting if the skin is broken. Echinacea tablets are also available if you prefer.

Propolis for cold sores

Propolis is a waxy antiseptic that honeybees make from tree resins to protect their hive from infection. Propolis has antiviral and antibacterial actions, and is traditionally used as a salve to hasten wound healing. Cell studies suggest that propolis is more effective against Herpes simplex viruses than aciclovir. The combination of the two also had a synergistic effect that was better than acyclovir alone.

A study involving 90 people with recurrent herpes found that those using a propolis preparation four times a day healed more quickly than those using aciclovir or placebo. After 10 days treatment, 80% using propolis had resolved, compared with 47% using aciclovir and 40% using placebo.

I recommend using the propolis and honey lip balm made by ‘Medicine Mama’ which includes protective beeswax and avocado oil.

Red light therapy for cold sores

Light therapy is increasingly used to boost immune healing responses. Low level light wavelengths in the infra-red range (1072nm) can suppress viral replication and promote cold sore healing when used during the tingling and blister stages. Using these devices for three minutes, three times a day for 2 days has been shown to significantly reduce healing time of herpes cold sores by 48  hours and may help prevent further attacks. Follow manufacturer’s instructions carefully.

Lysine for cold sores

L-lysine is an essential amino acid that is not produced in the body and must therefore come from the diet. L-lysine is metabolised to form acetyl-coenzyme A, which is essential for energy production, protein metabolism, growth, tissue repair and the production of antibodies.

L-lysine may help to reduce the frequency of Herpes simplex cold sore recurrences. It has been shown to suppress Herpes virus growth and to neutralise the stimulation of viral replication that can occur when another amino acid, L-arginine, is present in excess.

Clinical trials in the 1980s suggested that people who took daily supplements supplying 1000 mg 1-lysine reported significantly fewer cold sores than the control group. When they stopped taking the lysine supplements, their frequency of cold sore recurrences increased.

A clinical trial using a dose of 400 mg, three times a day, did not find any benefit from taking l-lysine to prevent cold sore recurrences, however. Higher doses may be needed (eg 1g l-lysine two to four times a day until ulcers heal).

L-lysine supplements may only work if you are lysine deficient, or when following a low L-arginine diet although this is controversial.

Home remedies for cold sores

Numerous home remedies are suggested for treating cold sores. These range from applying Listerine mouthwash and toothpaste to vaseline, Aloe vera gel, witch hazel, lemon juice and even cologne.

Most of these home remedies sting like fury and are best avoided. They mainly work by drying out the sore (which can then crack and hurt all over again) or by covering it with a soothing emollient. Instead of these home remedies, I recommend that you keep some licorice lip balm to hand (I have three – one in my first aid cabinet, one by my desk, and one beside my bed which I use as a lip conditioner). Then, at the first dreaded cold sore tingle on the lips you can start applying the balm.

I also increase my vitamin C dose to 1g per day if an outbreak threatens and in almost all cases, any lip cold sores are instantly stopped in their tracks.

What cold sore treatments have you found most effective? Please share your experiences via the comments below.

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