Harvest time in a village. It is the middle of the day and all are resting after lunch. The young peasant Nemorino, as usual, admires from afar the beautiful Adina, the rich and capricious farmer’s daughter (Quanto è bella). Adina, a passionate reader, is perusing a volume detailing the legend of Tristan and Isolde and laughing about the story of the love potion. She then tells the story to the peasants (Della crudele Isotta). Sergeant Belcore appears; he has recently been appointed a squadron commander. He publicly declares his affections for Adina and proposes to her (Come Paride vezzoso). Adina asks him to wait a little with her answer (Non è sì facile, Adina a conquistar) and invites him inside and brings him water. The despairing Nemorino reveals his love to Adina and threatens to kill himself but Adina dissuades him. Empty-headed and carefree, she laughs at his feelings (Chiedi all'aura lusinghiera).
The apothecary Dulcamara – a charlatan and phrase-monger – appears (Udite, udite rustici). He is selling a magic potion that cures all ills – from wrinkles to diabetes and paralysis. Nemorino rushes up to him and asks if he has Queen Isolde’s potion (L’elisir che desta amore). Delighted that he has found such a fool (Io ne son distillatore), Dulcamara sells Nemorino a bottle of Bordeaux, promising that it will work within twenty-four hours (by which time he himself will be far from the village). Nemorino, beside himself with joy, tries the potion and soon empties the bottle. He believes the potion is beginning to act (Caro elisir!). Confident that Adina will fall in love with him soon, Nemorino acts coolly. The enraged Adina agrees to marry Belcore in six days’ time. Nemorino is not at all concerned – after all, the potion will work by tomorrow (Ah! Va ben così!). But suddenly Belcore discovers that the next day he must depart for the war. Adina then resolves to arrange the wedding without delay. The desperate Nemorino begs her to wait (Adina credimi). But the farmer’s daughter takes her revenge on the peasant by inviting the entire village to the wedding. Nemorino is destroyed with grief (Dottore! Dottore! Soccorso! Pietà!).
The wedding banquet. The guests are drinking, enjoying themselves and singing barcaroles for two voices (La Nina Gondoliera). Adina is annoyed by Nemorino’s absence (Compita non mi par la vendetta). All enter the courtyard in order to sign the marriage licence and leave Dulcamara alone at the table. Nemorino appears. His despair has left him on the verge of suicide (Oh me infelice!). Dulcamara advises him to drink a little more of the magic potion. But Nemorino has no money left... He decides to become a soldier to Belcore and buy another bottle of Bordeaux with his salary (Fatti soldato et venti scudi avrai). The village maidens discover that Nemorino’s uncle has died and left him a vast fortune (Immensa eredità). Now they see Nemorino as incredibly handsome and they begin to flirt with him. “The potion works!” the peasant rejoices, having just finished his second bottle (È questa l’opera del magico liquore). Adina sees Nemorino’s hitherto unknown success with the girls and learns that he has enlisted in the army to win her heart. After all this she could fall in love with him. Dulcamara offers her the magic potion too but Adina turns him down: she believes only her own eyes (In quest’occhi è l’elisir). Nemorino rejoices at seeing Adina’s confusion (Una furtiva lagrima). Adina gives Nemorino back the recruiting statement which she has redeemed from Belcore (Prendi: per me sei libero) and, at last, falls into his embraces (Ti giuro eterno amor). Belcore decides to try his happiness with some other woman (Pieno di donne è il mondo). And Dulcamara’s magic potion, which brings love as well as money, is now selling like hot cakes in the village...