Sometimes you have symptoms that resemble a previous illness (e.g. fever and cough) that were treated with antibiotics. Why can’t the pharmacist "advance" you a box of antibiotics and let you bring the prescription later? Simply because your doctor is the only one who can make a correct analysis of your situation and check whether an antibiotic is necessary. This is why your pharmacist is not allowed to give you an antibiotic without a doctor’s prescription.