Throat ulcers are both painful and irritating and are often a sign of an underlying condition. We tend to think of ulcers as something which develops inside the mouth or on the tongue but they can occur in the throat as well. A crop of throat ulcers will appear as white spots on the tonsils which worsen over time to become grey, pus-filled sores. These sores will excrete pus after a time which leaves a nasty taste in the mouth. In most cases throat ulcers are a symptom of a medical condition which requires investigation and treatment.