Q I am 27-year-old man and have considerable pain when I urinate. A genito-urinary medicine clinic told me I have cystitis, possibly due to a stone in my bladder. I thought cystitis affected only women. GF from Wiltshire

A Cystitis is a general term meaning inflammation of the bladder lining. If the clinic has ruled out infection, then a bladder stone is possible. Men are three times more likely to develop these than women. Poor fluid intake and incomplete bladder emptying are common causes of stones.

You need more detailed investigations, including a dye x-ray called an intravenous urogram and possibly a cystoscopy, where a fibre-optic instrument examines the inside of your bladder. These will confirm if stones are present. If so, they can be removed surgically during the cystoscopy or broken up by ultrasound treatment.

Q I recently had a date with girl who had a cold sore near her mouth and I was nervous about kissing her. She says she gets these sores only rarely. How contagious are they? PK from Runcorn

A Very, and kissing someone with an active cold sore is the best way to develop one yourself. The sores are caused by the herpes simplex type 1 virus (HSV-1). About one in five people in the UK suffers recurrent cold sores but the condition is infectious only if the sufferer has an active sore.

You should avoid sharing cups or towels with anyone who has an active infection.

Attacks can be triggered by menstruation, emotional upset, heavy colds and strong sunlight. Aciclovir-based creams or tablets can help combat an attack if used at the first sign of a sore, usually tingling of the lip.

Q I am taking warfarin prior to treatment for an irregular heartbeart. Can I still take Viagra, which I buy online? I have done so in the past with no side effects apart from a flushed face. MC from Leicester

A First of all, please stop buying Viagra online. Some estimates indicate that half of all such tablets are counterfeit and potentially harmful. Taking warfarin and Viagra together does not usually cause problems, but I suggest you stop taking your Viagra now because of your serious heart arrhythmia, which needs to be corrected.

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