You can use acute to indicate that an undesirable situation or feeling is very severe or intense.

An acute illness is one that becomes severe very quickly but does not last very long. Compare chronic.

If a person's or animal's sight, hearing, or sense of smell is acute, it is sensitive and powerful.

An acute accent is a symbol that is placed over vowels in some languages in order to indicate how that vowel is pronounced or over one letter in a word to indicate where it is stressed. You refer to a letter with this accent as, for example, e acute. For example, there is an acute accent over the letter 'e' in the French word 'café'.