Dear doctor;

I get erections while kissing and caressing but once in bed with my lover, I cannot get an erection for several hours. This is causing me more and more distress and is putting me off relationships and sex. I have no trouble at all when masturbating. Am I impotent? Would using viagra help?

Tom, 27, Kabeza.

Dear Tom,

The way you have described things, it seems that there is no organic problem. In case of sexual impotence occurring due to diabetes, alcohol or some other problem, it is persistent. Apart from the  neurohormonal, vascular and physical factors involved in sexual activity, mental factors are also important. Anxiety due to some stressful situation, lack of adequate sleep, these facts can   affect the activity. Libido, duration of intercourse and achieving arousal are entirely subjective and vary from person to person There is no set pattern for a man. Many times one wants to copy somebody and then feels anxious afterwards. Learn to relax completely both physically as well as mentally. 

Use foreplay for sometime before the actual act. Viagra is useful only when used 30 minutes before the actual act. Once used, the effect does not last for another day. Moreover it can cause serious adverse effects like sudden shock and cardiac arrest. Hence it is not recommended in case like yours.