I looked up "euphoria" in the OED and was mildly surprised at the second meaning they have given it. Here I am not taking cocaine but my Hay Fever spray, what a relief to find my symptoms easing very quickly thus imparting a sense of euphoria.
Meaning 2
1728–
Pathology. ‘A word used to express well-being, or the perfect ease and comfort of healthy persons, especially when the sensation occurs in a sick person’ (New Sydenham Soc. Lexicon). Now frequently in non-technical contexts: a state of cheerfulness or well-being, esp. one based on over-confidence or over-optimism.
