your problem is a characteristic of cholinergic urticaria. it is a type of urticaria where patients are allergic to their own sweat. so whenever a patient sweats for example due to heat sun stress exercise. etc. the patient develops hives. levocetirizine can suppress the problem till you take it. once you stop taking it your problem will recur. the management actually depends on you. if you are fine taking cetirizine daily then no harm or else you can go for biological treatment which is a new form of treatment. it can permanently cure the problem and you may no longer require cetirizine. they are very safe with almost no side effect. for further information contact a dermatologist online --> <link>
kindly suggest me a therapy to overcome heat allergy.