It is the harvest season and the lovesick young peasant, Nemorino, gazes longingly at the haughty and beautiful Adina in whom he is unable to arouse even the slightest response. She is reading the tale of Tristan and Isolde to the resting harvesters, all of whom wish that they, too, might drink the fabled elixir by which Isolde succumbs to Tristan. The swaggering Belcore, sergeant of the local garrison, enters with his troops and overbearingly presents himself to Adina who is unimpressed. Nemorino renews his suit, but Adina merely laughs and tells him he should go to the city to visit his dying uncle. Doctor Dulcamara, a notorious quack, makes his appearance and tells the assembled crowd of his famed tonic which cures all ills. Nemorino recalls the love potion and asks if Dulcamara has any to sell. The quick-witted doctor produces a bottle of heady wine and assures Nemorino that this is the very potion he desires. Drinking it at once, he feels himself suddenly emboldened. He spurns Adina who has returned and she, out of spite, announces that she will marry Belcore within the week.

Inside Adina’s house the villagers are preparing for her wedding. After the notary arrives, all go to an inner room to witness the signing of the contract, except Doctor Dulcamara, who is more interested in the food remaining on the banquet table. Nemorino, filled with despair, pleads with Dulcamara for another bottle of the love potion, but unfortunately he does not have enough money. Belcore, hearing of his dilemma, suggests that Nemorino accept a commission in the army for which he will be paid twenty ducats. Nemorino signs up at once, takes the money, and rushes off to buy some more elixir. Unknown to him, his rich uncle has just died and left him a fortune. The village girls are elated and when Nemorino returns, after having consumed his second bottle of elixir, they become very attentive. Of course, he is convinced that the potion has at last taken effect. Adina comes upon the scene and is distressed to find Nemorino so indifferent to her forthcoming marriage. Though Nemorino observes Adina’s tears, he is helplessly dragged away by the ambitious girls.

Doctor Dulcamara finds Adina pining alone and offers her a bottle of his magic potion. He relates the case of a certain Nemorino who sold himself into the army in order to buy the smallest bit of his wondrous brew. Hearing this, Adina realizes how deeply Nemorino really cares. She tells Dulcamara that she has a better potion at her disposal – flirtation. With this she will win Nemorino again.

The young peasant has escaped from his ardent friends, and now alone, reflects on Adina’s unhappiness. She appears. To prove her love for him she has bought back his army commission, and flirtatiously, yet sincerely, Adina reclaims Nemorino’s love. While the two happily embrace, Dulcamara returns with the townsfolk. Shrewdly he tells the crowd that it is his wondrous Elixir of Love which has brought this great happiness. Sergeant Belcore takes his disappointment like a soldier, and, as the lovers rejoice, everyone else surrounds Dulcamara, showering him with money in exchange for the magical brew.