Allergy is a type of hypersensitivity disorder comes under the category of immune system.  A numeral conditions caused by hypersensitivity of the immune system to something in the environment typically causes no or little problem in maximum population. These diseases include food allergies, hay fever, allergic asthma, dermatitis, and anaphylaxis. Symptoms may include itchy rashes, red eyes, runny nose, shortness of breath and swelling. Among 4 (four) types of histamine receptors in human body H₁ receptor is found in Peripheral nervous system which includes smooth muscles, epithelium layer & also in Central Nervous System. Its function, in central nervous system is to maintain body temperature, sleep and wake cycle, appetite, endocrine homeostasis, mood, memory and learning. In peripheral nervous system it is responsible to cause Bronchoconstriction, Vasodilatation, Responsible of Hives because of insect stings it causes pain, itching, which is also responsible to cause Motion sickness and Rhinitis. Oral medications like H₁ Blockers and decongestants are used to reduce symptoms. People taking H₁ receptor antagonist as a self-medication can central for more severity of his/her cases. Taking as a self-medication, they do not take any recommended dose, so dose can fluctuate as over dose or under dose. As by taking Loratadine for a long term may lead to drug resistance and also they are addicted to these drugs. A descriptive cross sectional study is publicized by collecting the patient data on predesigned questionnaire.

Methodology: Total number of 300 patients was enrolled via purposive sampling from different hospitals, pharmacies and clinics of Hyderabad, Pakistan. The study was observational & then the dose of total sample size was compared with the standard British National Formulary 71 edition and the data was analyzed by using SPSS software version 22, Microsoft Excel & other statistical tools.

Results: Patients having flu were more in number of 28%; 22.66% of common cold; 21.33% of skin rash; 18.33% of cough and 9.66% patients were of others which includes Urticaria and Red Flare. 23% patients used Loratadine which is 2^nd generation H₁ receptor antagonist (anti-histamine) 22% patients were taking Chlorpheniramine which was the only 1^st Generation H₁ blocker used among the patients. 45% patients were taking BD dose, 27% of OD & 25% patients were taking TDS and only 3% patients were taking SOS. Through the survey & pre-designed questionnaire, it was found that most of the patients were taking anti-histamine without the prescription of doctor (174 / 300 patients) as all anti-histamines are easily available in all pharmacies and the patients were experiencing side effects because of no dose adjustment by Doctor or a Pharmacist. Among all 59.3% patients were experiencing Dry nose, 57.6% head ache, 56% of dry mouth, 58.6% patients were experiencing drowsiness, 52.3% were feeling sickness and 34.6% patients were having problem in driving due to hang over effects.

Conclusion: It is concluded that patients were using H₁ Receptor antagonists because of easy availability of drugs in our pharmacies and because of unavailability of Pharmacist in pharmacies, so frequent use of anti-histamine with no dose adjustment can lead severe side effects with drug dependence.

Key Words: Aberrant use; H₁ Blockers; Anti-allergic; Allergic Patients.