Garlic is full of antioxidants so eating garlic is pretty good for your overall health but yes you can eat too much of it and when you do it could possibly lead to bleeding of your intestines, bad breathe, diarrhea, body odor, vomiting, heartburn, nausea and even a burning sensation in both your stomach and mouth.
You would have to eat a heck of a lot of garlic for it to really cause any harm to you though so I wouldn't worry about eating too much garlic as long as you haven't eaten more than 20 to 25 cloves of garlic you should be just fine.