The novel's most prominent theme suggest that lovesickness is a literal illness, a plague comparable to cholera. Florentino Ariza suffers from lovesickness as one would suffer from cholera, enduring both physical and emotional pains as he longs for Fermina Daza. In Chapter 2, Florentino is so ill from worry that Fermina will not respond to his declaration of love, his mother calls on his's godfather, a homeopath, who initially mistakes Florentino's lovesickness for cholera. Again in Chapter two, Florentino complicates his emotional pain with physical agony when, he vomits after eating flowers and drinking cologne so that he may know Fermina's scent. Florentino's illness, it can be argued, transcends the physical to the psychological, for though he is sick in his heart and in his stomach, he is compulsively obsessed, and therefore mentally disturbed.
The theme of love as a plague culminates in the book's final chapter, in which Florentino orders the Captain of the ship on which he and Fermina are aboard to announce, falsely, that there is an outbreak of cholera on board. Although there is not a case of cholera aboard the ship, the claim is not entirely false, for Florentino has been infected by a relentless passion for Fermina since the day she rejected him in the Arcade of the Scribes, fifty-one years, nine months, and four days ago. His passion has persisted much like a deadly plague of cholera, for Florentino is literally plagued by love.
Aging and death are prominent concepts which first emerge upon the death of Jeremiah Saint-Amour and are expanded throughout the novel. Dr. Juvenal Urbino realizes, upon seeing Saint-Amour's body, that death is not a "permanent probability," as he has always imagined, but, for the first time in his long life, truly and fully understands that death is an actual, irreversible, and immediate destiny. Once a man of great strength and authority, Dr. Urbino is, in his old age and debilitated physical condition, forced to use the toilet like a woman. In old age, the Doctor, now pathetic and dependent, is belittled and enfeebled by his own maturity, for his mind and body have become unfamiliar, their changes frightening signs that he will soon succumb to death.
After receiving Fermina's reply to his second profession of love, Florentino lies absolutely still in bed, "more dead than a dead man.". Indeed, Florentino is growing very old, as is Fermina, and must now suffer the injustices of old age, as he once had to suffer the injustices of his youth. There is much bias against the elderly, and there exists a hurtful stereotype that any person in their elder years is limited, both in physical and mental capacities. When América laughs at Florentino's sober news that he intends to marry, she cannot take him seriously only because he is an old man, and in her own view, and in popular belief, old people simply do not marry; for to be in love after mid-life seems against some unwritten social rule. Further proof of bias against the elderly is Ofelia's opinion that love among older people is nothing more than "disgusting."
Throughout the fifty-one years, nine months, and four days that Florentino is apart from his beloved Fermina, he seems to revel in the pain his unrequited love inflicts. Strangely, Florentino enjoys the suffering he endures for love; when he must spend three nights in a jail cell on account of the violin serenade he plays for Fermina, he feels martyred, satisfied for having sacrificed himself in the name of love. The marathon romantic torment Florentino suffers sustains him, for he sees his anguish as a gratifying, strengthening experience that will lead him to his ultimate desire: Fermina. When Lorenzo Daza threatens him with a gun, and tells him to stay away from his daughter, Florentino challenges him and declares that there is nothing more noble than to die for love. Florentino enjoys the anguish he feels when in love, and induces it when he ingests flowers in Chapter 2, for if he cannot be with Fermina, he must feel something, even if it is pain, to know that he is alive. The flowers, like his love for Fermina, make him violently ill, and deliver intense emotional and physical agony.