Cold sores

Q This time of year, I always find that my cold sores flare up. Suncreams help, but I often end up relying on strong over-the-counter remedies like Zovirax because the pain is too unbearable. Is there a more natural way to treat them? - LV, Manchester

A Cold sores, fluid-filled blisters on the edge of the lips, are caused by herpes simplex-1 virus. Over a two-week period, the blisters, which are contagious, eventually break, ooze and crust over before healing. Recurrences are common, and triggered by stress, sun exposure, illness and menstruation.

Topical ointments such as Blistex and Campho-Phenique are often recommended to curtail outbreaks and ease the pain. Antivirals such as aciclovir (Zovirax) or penciclovir (Vectavir, Denavir) may also be prescribed. But other, less drastic options may be just as effective.

The herpes simplex virus needs the amino-acid arginine to thrive, but the amino-acid lysine inhibits it. So, you may wish to avoid foods with high arginine-to-lysine ratios such as nuts and chocolate. Supplementing with lysine can reduce outbreaks, but you may have to experiment to get the right dose for you. Evidence suggests an intake of 1-3 g/day, or as little as 312 mg/day in some cases (Dermatologica, 1987; 175: 183-90; Acta Derm Venereol, 1980; 60: 85-7). Non-fat yoghurt and other non-fat dairy is also a healthful way to increase lysine intake.

Vitamin C inactivates herpes in test-tube studies, and human studies show that 200 mg taken three to five times daily can reduce the duration of symptoms by 57 per cent (Oral Surg, 1978; 45: 56-62).

Here are a few other useful remedies:

* Zinc preparations can stop virus replication in the lab (Med Hypoth, 1985; 17: 157-65). Applying a zinc-sulphate solution daily to sores, and then at regular intervals in between outbreaks can also reduce their occurrence (Br J Dermatol, 1981; 104: 191-4).

* Vitamin E oil applied to newly erupted cold sores at regular intervals throughout the day can quickly reduce pain and speed up healing (Dent Surv, 1976; 52: 50-1; Br Dent J, 1980; 148: 246).

* Propolis ointment four times a day may help, though it has only been studied in genital herpes, where it was found to be more effective than topical aciclovir (Phytomedicine, 2000; 7: 1-6).

* Lemon balm is antiviral and can speed cold-sore healing (Phytomedicine, 1994; 1: 25-31). Using a cream with 1 per cent 70:1 extract of lemon-balm leaf four times a day for five days can reduce the number of blisters and the intensity of symptoms (Phytomedicine, 1999; 6: 225-30).

* Witch hazel contains antiviral proanthocyanidins (Planta Med, 1996; 62: 241-5). Applying a cream with 2 per cent witch hazel-bark extract six times a day for three to eight days can reduce the size and spread of blisters (Z Allerg Med, 1998; 74: 158-61).

In traditional herbal medicine, ointments and tinctures of herbs such as liquorice, St John’s wort, goldenseal, myrrh and Echinacea, applied topically, have promoted healing of cold sores.