Dr. Paul Marshall, a neuropsychologist at Hennepin County Medical Center in Minneapolis, Minnesota, states that a person suffering from allergies has double the risk of developing depression. Additionally, a consultation with an allergist triples the likelihood of having depression. The correlational study is not conclusive, but allergy-connected mood changes usually boil down to mild depressive symptoms like sadness, lethargy and fatigue.
An allergic reaction is an immune response that releases cytokines, protein molecules used in communication between cells. For example, cytokines induce feelings of sickness that often accompany the flu. A 2002 study conducted by Marshall found that allergic reactions to ragweed pollen cause significant fatigue and mood changes in some patients. More recently, Dr. Teodor Postolache published a study investigating the association between suicidal indicators and allergies. Postolache’s group noted a peak in suicide rates from April to June.
Antihistamines used to treat allergies can also contribute to low moods. The side effects of allergy medications can heighten irregular sleeping patterns that can increase irritability. The major antihistamines, including Allegra, Claritin and Zyrtec, can also lead to insomnia.
Dr. Michael Silverman, Assistant Professor of Psychiatry at Mount Sinai School of Medicine, asks people not to blame allergies for deeper emotional issues. Even if some people have a direct mood response from allergies, allergies are not always the best explanation for feeling depressed.