People with allergies have extra-sensitive immune systems which react to normally harmless substances. Allergens that sometimes produce this reaction include plant pollen, dust mites, or animal dander; plants such as poison ivy; certain drugs, such as penicillin; and certain foods such as eggs, milk, nuts, or seafood.

The tendency to develop a particular kind of allergy is inherited, and allergies usually begin to appear in childhood, but they can show up at any age. Common allergies for infants include food allergies and eczema (patches of dry skin). Older children and adults may often develop allergic rhinitis (hay fever), a reaction to an inhaled allergen; common symptoms include nasal congestion, runny nose, and sneezing. It is best to avoid contact with the allergen, if feasible. Some people with allergies also have asthma, and allergens are a common asthma trigger.

Conventional treatment can help in acute episodes but fails to give long term relief. Homeopathy can give long term relief in this condition. Homeopathic medicines administered after detail case study enhances the immunity of the patient and prevents recurrent episodes and intensity of each episode is reduced significantly.