my doctor prescribed me viagra 100mg as needed before intercourse and yohimbine hcl 5.4mg three times a day. I noticed that some take yohimbine hcl at a dose of 10-20mg just before sexual activity rather than the prescribed three times a day. what i did was took viagra 1 hour before sexual activity and 10.8mg of yohimbine hcl half an hour later. I don't think I noticed any firmer erection when yohimbine was included but what i noticed was as soon as i insert my penis in her vagina i want to ejaculate and it is very hard to hold it back... Is this normal or i shouldn't combine viagra and yohimbine hcl together.Thanks