You might ask him to see his doctor first or to at least read the following:
SIDE EFFECTS:
Headache, flushing, stomach upset, heartburn, nasal stuffiness, diarrhea, dizziness, or lightheadedness may occur. Vision changes such as increased sensitivity to light, blurred vision, or impaired blue/green color discrimination may also occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Rarely, a sudden loss of eyesight in one or both eyes (NAION) may occur. This may or may not be due to sildenafil. If this serious problem occurs, seek immediate medical attention. You have a slightly greater chance of developing this serious eye problem if you have heart disease, diabetes, high cholesterol, certain eye problems (”crowded disk”), high blood pressure, are over 50 years of age, or if you smoke.
Sexual activity may put extra strain on your heart, especially if you have heart problems. If you have heart problems and experience any of these serious side effects while having sex, stop and seek immediate medical attention: severe dizziness, fainting, chest pain, nausea.
For males, in the very unlikely event you have a painful or prolonged erection lasting 4 or more hours, stop using this drug and seek immediate medical attention, or permanent problems could occur.
Rarely, sildenafil may cause sudden hearing problems, or ringing in the ears. Seek immediate medical attention if these effects occur.
A serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching, unusual swelling, severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

Not unless your BF has talked to a doctor. If he has, and he really actually has an ED problem, then fine. If he’s buying it off the street, it’s a really bad idea. Aside from not knowing that he’s actually ingesting Viagra, there are definite health risks in taking it when you don’t need it.
If his concern is that he wants an extra edge or punch (or the ability to get it up more than, say, three or four times), then you two need to talk.

if he wants it Therese not much you can do to stop him; all i can say is….get ready to have allot of fun
but be careful im not shure why but when my friends husband started taking it he would get very ruff with her (but he was a prick!)

There is not enough information here for a reasonable answer.
How old is he?
How is his health?
Does he have a problem in the first place?
Drugs such as this are not toys so if it ain’t broke, don’t fix it!

My ex and I did it. It’s fun. Cialis worked the best because it works for 36 hours, instead of right-then-and-there action. The only problem he could have with Viagra is that he’ll have a hard-on for a few hours.

If he is 60 yeah. But if he starts taking it young, and continues to take viagra he will become impudent. Which would be VERY bad.

I was considering this as well, curious on answers.

Should you LET him? Hmmmmm Very interesting

It’s highly unlikely he even needs it,and if your s*x life is good. Why try to fix something that isn’t broken?

Mmmmmmmmmmmm BF.

lucky you

of coarse
bang