Dr Sylvester Mooney answers all your health questions!

Dr. Sylvester Mooney is the Medical Director at webdoctor.ie. He studied in UCD and he qualified in medicine from the Royal College of Surgeons in Dublin. The areas of women’s health, travel medicine, reactive depression and men’s health are of special interest.


Dear Dr,

I’m going on holidays this month and I usually suffer really badly from cold sores whenever I’m in the sun. Is there anything I can take before I go away to try avoid the dreaded eyesore while I’m trying to enjoy the sun?

Linda, by email


One of the great joys of a sun holiday is feeling the warmth of the sun’s rays. However these rays contain Ultraviolet (UV) light and UV rays have a suppressive effect on the cells of the immune system as they are deployed in the skin. When this happens, the virus which causes cold sores (Herpes Simplex Virus, which lies dormant for much of the time in the nerve cells in the skin) becomes active again and causes the typical skin tingle, which indicates that it will ‘bloom’ within several hours to cause the full, blown cold sores. These can take 10 days to finally settle and are very unpleasant to deal with. So the trick is to have suitable antiviral tablets ready to start AS SOON as you feel the tell tale skin tingle. If you are ‘tuned in’ to these early changes, then starting the antiviral tablets will hopefully abort the full attack. These antiviral medications are prescription only so the next time you visit your local doctor, ask for a course of Valciclovir tablets 500 milligrams; to be taken at a dose of one tablet twice a day. Ask your doctor to do a repeat prescription so that you can take a second course as these can occur in a cluster fashion.