Urine often smells bad in the morning because it is more concentrated after a night of sleep, according to Mayo Clinic. Dehydration can also cause urine to have a bad smell, as the National Health Service of the U.K. explains.
Certain drinks and food, such as garlic, coffee, asparagus and beer, can cause urine to smell bad, notes the NHS. Certain medications may also contribute to foul-smelling urine, as can mineral supplements and vitamins. Medical conditions, such as poorly controlled diabetes and problems with the kidneys and bladder, can also cause it. Drinking more fluids, especially during hot weather and when exercising, can improve the smell of urine.