I've used viagra and E / Speed on a number of occasions, being careful to only have a tiny bit of viagra, as I found it takes surprisingly little to overcome and vascular constriction affects from amphetamines.
I found the stimulatory effects from the E or whizz meant for me that staying power etc was greatly enhanced.
After having done this several times without any noticeable adverse effects, one night I felt a strong facial peripheral stimulation which was extremely uncomfortable. Thinking it was probably a one off, some weeks later after a nice E' vening with my girl, I popped 1/4 of 100mg Viagra and within minutes my face and chest were bright red. I started to panic slightly as I felt my head was going to explode!
Really bad stuff, but it gradually it subsided to lower regions allowing things to roll on. I tired this one more time to find it was again the same. The initial rush -thats what it feels like- is similar to amyl, which I detest. So I no longer use this combo, instead going for a few days preload if possible with tribulus and a mixture of minerals. It
seems to make a big difference. I also once tried rubbing liberal amounts (~50+x rec dosage) of dermo testosterone mixed with DMSO on my skin a few days before....
....err, we'll talk of that some other time
There are lots of things to try if this complaint is a real bother. Although it may sound scary, there's also caverject, an injectable type of PDE inhibitor. Papaverine, related to morphine was once used but this has been largely replaced by prostaglandin E1, which until recently was only available in a form which had to be kept refrigerated until using. Apparently a mixable powder is now available.
The advantage with this method - besides giving a rock hard erection - is is that the drug is injected locally and so should have little general cardiovascular effect. The syringe is conveniently packaged and comes with an instruction video. People I know who use this method regularly say it works like a charm, doesn't hurt a bit if done properly, and
can give you staying power into the next day, although it is supposed to only last an hour or so. To avoid any possibility of priapasm when using these drugs, a tablet may also be given by the doctor which causes the penis to deflate.
If erectile dysfunction is not normally a problem, I believe if you're not overtired, aren't too smashed, haven't gobbled/snorted too many and are with your heart's desire; sex is easy and always possible. Just don't be in too much of a rush - sleep for a while first if you need- even viagra can't sometimes compete with a wandering mind. Most of all, remember it's the drug causing the lack of action. If you're low on serotonin and dopamine reserves you're at a distinct disadvantage from the start.
Please heed the warnings regarding amyl nitrite or other nitro/nitrite based compounds if using Viagra. This is a very dangerous combo as the enzyme disabled by viagra results in the effects from nitros/nitrites to be increased significantly causing possible heart cardio/ vascular conditions.