A variety of other tests may be used to diagnose allergies or to rule out other conditions that may produce similar symptoms. These may include:

• Nasal smear. Examination of nasal fluids. Patients blow their nose onto a plastic sheet. Fluids are transferred to a plastic slide and tested for the presence of eosinophils, a white blood cell that can indicate the presence of an allergy. This test is rarely done.
  
  
• Nasal endoscopy. Viewing nose and/or sinus cavities using a special telescope (nasal endoscope). Nasal mucous membranes that are swollen, pale and bluish may indicate the presence of an allergy.
  
  
• Chest, nasal and/or sinus x-rays. An image of the chest, nose or sinuses produced on film paper or fluorescent screens using low doses of radiation. X-rays may be taken to rule out other diseases such as emphysema, cystic fibrosis, tumors, foreign body interference and nose structure malformations.
  
  
• Electrocardiogram (EKG). Records the electrical activity of the heart. These may be used in older patients experiencing shortness of breath to rule out a heart–related problem.
  
  
• Pneumatic otoscopy. Viewing the patient's ear drum both at rest and during movement in response to a change in pressure. It may be used to rule out ear infections as a source of certain symptoms.
  
  
• Tympanometry. Determines the patient’s response to sound under different air pressures. It may be used to rule out fluid in the middle ear, damage to the ear drum (tympanic membrane), impacted ear wax and other conditions.

A physician who suspects another respiratory disorder (e.g., asthma) may order other tests, such as spirometry or other pulmonary function tests.