Hello and Welcome to healthcaremagic
Urticaria OR hives can occur due to various causes like(to name a few):
--Infections(bacterial , viral, fungal)
--Drugs(Pain killers/ antibiotics etc)
--Certain foods and food additives/preservatives
--Physical Urticaria: Cold temperature, Heat, Pressure(Prolonged Standing, Sitting), Dermaographism etc.
--Cholinergic Urticaria: in response to strong emotions, exercise, spicy food etc
--
Autoimmune disorders like SLE, RA etc.
Many cases have no underlying cause and are known as 'idiopathic urticaria'
An oral antihistamine like
Fexofenadine (Allegra 180 mg tab) OR
Loratadine (Alaspan 10mg tablet) once or twice daily for a week would be suitable. They are non-sedating and wont affect your alertness level.
A topical soothing lotion like
calamine would help you symptomatically.
take care
regards