Hi Thank you for asking HCM I have gone through your query.Your problem is most likely urticaria due to an allergic reaction to doxycycline. You should remember this drug and tell if any doctor prescribe it on future. For such conditions i treat my patients with antihistamines and corticosteroids. If severe itching is there i give them one dose as injection of those two. I aso advise them to apply calamine lotion locallyt to get soothing effect.Hope this may help you. Let me know if you have any further query.