Risk factors

There aren't many known risk factors for anaphylaxis, but some things that might increase the risk include:

• Previous anaphylaxis. If you've had anaphylaxis once, your risk of having this serious reaction increases. Future reactions might be more severe than the first reaction.
• Allergies or asthma. People who have either condition are at increased risk of having anaphylaxis.
• Certain other conditions. These include heart disease and an irregular accumulation of a certain type of white blood cell (mastocytosis).