Im a 59 year old female who two-three times a year experiences allergic reactions for no apparent reasons.  They have occurred while sleeping, walking in either cold or warm conditions, or just sitting.   My doctor has claimed I have a conditional known as a heat induced anaphylactic reaction.  So far I have not experienced difficulty breathing during a reaction, but my body becomes covered with hives and my face will swell.  Any insight would be much appreciated.
Hi, Welcome to health care magic, There can be plenty of causes for allergic hives or urticaria like Chat Doctor. Generally urticaria disappears after few minutes without any treatment if it persists then you may require further treatment with antihistamines like cetirizine or steroids and mast cell stabilizers. So, if you are suffering from this then first thing you don't have to worry. In the majority of cases, It subsides by itself, or you may take antihistamines like Ben