The greatest source of irony in "The Yellow Wallpaper" stems from the negative impact that the narrator's treatment has on her well-being. Medical treatment is very much intended to make a patient better and is prescribed by physicians to better a person's physical and mental health. However, in "The Yellow Wallpaper" the treatment that the narrator receives has the opposite impact, making the narrator's condition significantly worse. The irony is further illuminated when one considers what might have happened if the narrator had received no treatment at all. It is likely that having been allowed to go on with her normal life and interact with others she would have recovered significantly and more quickly than she does with medical treatment. Moreover, this is especially ironic given that the treatment that she receives stands in direct opposition to what is generally recommended for women in her condition (walks in the outdoors and communication with others). This connects strongly to the underlying thematic messages of the story because it demonstrates how men in control of women's lives often suppress the true and natural desires that lead to female fulfillment.
There are three types of irony. Verbal irony is when someone says something but means something else, this has been modernized under the name of sarcasm. Dramatic irony is when their is a contrast between the reader's knowledge and what the characters know. Situational irony refers to when a character's actions have the opposite effect of what they intend.
All three types of irony are shown in The Yellow Wallpaper. Verbal irony occurs when she says "I am glad my case is not serious" when her case is clearly severe and she understands that.
Dramatic irony is shown when the narrator thinks the room she has been condemned to was once a nursery when it is clear to the reader that the room used to house an insane person.
Situational irony is shown when John's treatment backfires worsening his condition and driving his wife insane.