Eddie Kaspbrak's asthma

Eddie Kaspbrak's asthma is the defining physical and psychological condition of his childhood, a psychosomatic illness that shapes his identity, his relationship with his overbearing mother, and his role within the Losers' Club. The condition is not a physical ailment but a manifestation of deep-seated anxiety and maternal control, a fact that is brutally revealed to him by the town pharmacist, Mr. Keene. Yet, paradoxically, the power of belief—both his own and that of his friends—transforms his placebo medicine into a genuine weapon against the supernatural horror of It.

The Nature of the Condition and Its Revelation

Eddie's asthma is characterized by a sudden tightening of his throat and chest, a whistling breath, and a desperate need for his aspirator. This device, a plastic squeeze-bottle labeled "HydrOx Mist," is his constant companion. The condition is so severe that it dictates his daily life; his mother, Sonia Kaspbrak, uses it as a justification for her constant, smothering care, insisting Eddie is "delicate" and must avoid any physical exertion. The truth is revealed by Mr. Keene, the pharmacist, who tells Eddie that his medicine is nothing but "water with a dash of camphor thrown in to give it a medicine taste." Mr. Keene explains that Eddie's asthma is a "mental weakness," a nervous tightening of the diaphragm ordered by his mind or his mother. This revelation shatters Eddie's understanding of his own body, but he cannot immediately abandon the aspirator, as the habit of belief is too strong.

The Aspirator as a Weapon and a Symbol

Despite its placebo nature, Eddie's aspirator becomes a powerful tool in the Losers' Club's fight against It. During their first confrontation with the Crawling Eye in the sewers, Eddie, with his broken arm, charges forward and triggers the aspirator into the monster's face, screaming "BATTERY ACID, FUCKNUTS!" His absolute belief that the mist is acid makes it so, and the Eye recoils in pain. Later, in the final battle, he again uses the aspirator, this time shooting it down the throat of the Spider-It, causing a terrible rupture. The aspirator, a symbol of his weakness and his mother's control, is thus transformed into a symbol of his courage and his power to shape reality through belief. It is a physical manifestation of the novel's central theme: that childhood faith can make the impossible real.

The Struggle for Agency and the Final Act

Eddie's asthma is inextricably linked to his struggle for independence from his mother. After Mr. Keene's revelation, Eddie confronts Sonia in the hospital, using the knowledge of the placebo as leverage to force her to allow his friends to visit. This is a pivotal moment of rebellion, where he begins to claim his own agency. His final act is one of complete self-sacrifice and courage. In the 1985 confrontation, he attacks the Spider-It, and it bites off his arm. As he lies dying, he feels a profound clarity, a sense of all the impurities flowing out of him. His last words are a gentle correction to Richie: "Don't call me Eds." This final assertion of his own name, his own identity, is the ultimate victory over the condition that defined him. His death is a direct result of his bravery, a final, decisive act of agency that frees him from the asthma and the mother who created it.