Set in Italy in 1830, the story asks whether love is from the heart or a magic potion. Adina reads a story to a group of peasants about how Tristan won the heart of Isolde by drinking a magic love potion. At a distance Nemorino, a young man, laments he has nothing to offer Adina but love. After the story, Sgt. Belcore swaggers in with his troop. The soldier's conceit amuses Adina, and he proposes.

When Adina and Nemorino are alone, he awkwardly declares his love. Dr. Dulcamara arrives in the village with his wagon filled with bottles of a powerful potion - an elixir of love (really bottles of cheap wine).

Nemorino buys the wine and hastily drinks it, and Adina enters to find him tipsy. Certain of winning her love, he pretends indifference. To punish him, Adina flirts with Belcore, who persuades her to marry him at once. Nemorino begs Adina to wait one more day, but she ignores him and invites the entire village to her wedding feast. All join in praising Dr. Dulcamara and his magic elixir.

Nemorino's uncle has died and willed him a fortune. The women of the village hear about his newly acquired wealth and besiege him with attention. Unaware of his new wealth, he believes the attention is from the elixir. Adina and Dr. Dulcamara arrive in time to see him leave with a bevy of beauties. Hoping to sell Adina a bottle of elixir, the "doctor" claims that Nemorino's popularity is due to the magic potion. Adina replies she will win him back through her own charms.

Will Adina be able to recapture Nemorino's love? Will the doctor escape undetected? Will Sgt. Belcore fight for Adina? All questions will be answered at the performances.