Urine doesn’t usually have a strong smell. But some foods -- especially asparagus, which has a smelly sulfur compound -- can change the odor. So can vitamin B-6 supplements. When you’re dehydrated and your pee gets very concentrated, it can smell like ammonia. If you catch a whiff of something really strong before you flush, it might also be a sign of a UTI, diabetes, a bladder infection, or metabolic diseases. Go to the doctor.