There are three treatment approaches.
Avoiding the allergen. This is possible for some allergies, such as for dust mite, pet hair and food allergies.
The proper medication is administered locally or orally. While this treatment alleviates symptoms and suppresses the allergic reaction, it does not treat the actual allergy.
Hyposensitisation / specific immunotherapy
Hyposensitisation means that the allergen is administered to the body in gradually increasing dosages. This teaches the immune system that the allergen does not pose a hazard. This treatment takes three to five years before it can be successful in long-term. The specific immunotherapy can be given subcutaneously (a shot in the upper arm under the skin) or sublingually (drops or tablets under the tongue).