I LOVE garlic. I want to know why garlic tastes so good and why garlic smells so good, but the instant you get it on your breath, it’s the most repulsive thing in the world.
DUH! Your breath turns bad to keep the vampires away. Didn’t they teach you anything in school? 
HUGS!
Sqrl
When our bodies digest garlic, certain chemicals in the garlic enter our blood stream so the bad smell lingers much longer than other odors which are confined to the mouth or underarms.
You can try brushing your teeth vigorously after eating garlic, but it won’t help. It’s inside you for quite a while.
I like both onion and garlic but cooked, not raw, and I have never had any odor problems. I think it is only raw that they have this effect.
The more you cook garlic, you lessen the flavor and also the aftereffects.
Try roasting garlic until it becomes as smooth as butter. Then you can spread it on bread, MMM…
to slightly expand on what BobT said…
"We’ve all probably had experience with bad breath caused by the first category. We eat a meal and then suffer with embarrassing bad breath later. The culprit is usually certain foods like garlic and cabbage which contain sulfur compounds. These sulfur compounds are what causes breath to smell bad.
The foods are ingested and their sulfur compounds are absorbed by the stomach into the bloodstream. Contrary to popular belief the bad breath doesn’t come from the sulfur compounds working their way back up into the mouth from the stomach .
Rather, the sulfur compounds are absorbed by the small intestine, enter the bloodstream, and then are carried to the lungs. Here they are eliminated by the lungs in the air that we exhale ! Amazingly many of these sulfur compounds are also excreted in sweat from the skin and in urine for hours to even days after the food is eaten."