Abstract: Apparatus and methods are disclosed for treating allergic rhinitis (seasonal and perennial hay fever), by application of flash lamp radiation. The nasal cavity can be illuminated in a safe and effective manner, with non-coherent light from a flash-lamp or other suitable source. This illumination can be accomplished in any suitable manner, including by use of a handheld device. Such handheld embodiments may contain a power source (battery or AC), control circuitry, light source (flash-lamp or diode laser), lens (focusing or non-focusing), light filter, and/or fiber-optic for delivering light to the nasal cavity. Embodiments include using any suitable light energy, such as visible light in the red wavelengths with a power output of 1 to 10 Joules per cm2. The device can be pre-programmed to deliver a specified amount of light in a specified amount of time using multiple pulses (in the case of a flash lamp) or a continuous wave (in the case of a diode laser).