Does food allergy cause immediate reaction

Of course not. The onset time of food allergies varies greatly, and it is by no means as simple as "feeling sick immediately after eating" as everyone thinks. I have been working as a nurse in the allergology department for almost 6 years, and I have encountered too many people who hold the misunderstanding that "if you don't feel uncomfortable immediately after eating, it must not be an allergy". They either don't take it seriously and are almost in danger, or they miss the diagnosis for a long time and can't find the cause of the discomfort.

The 6-year-old boy who was admitted last week has the most typical form of immediate allergy. His grandma fed him half an unpeeled peach at home. After just two chews, the boy complained that his mouth was numb. When he came in, his entire lips were swollen into "little sausages." He kept coughing and holding his breath, and he couldn't even speak clearly. This is an immediate type of allergy mediated by IgE. It usually attacks within minutes to 2 hours after eating. It occurs very quickly. In severe cases, laryngeal edema and anaphylactic shock may occur quickly. It is also a relatively well-known type of allergy and is generally not confused with other problems.

Don’t think that only this kind of “menacing” allergy is called an allergy. What we encounter every day and are more likely to be missed are actually delayed-type allergies that attack silently. A while ago, a girl in her 20s came to see a doctor. She said that she had been suffering from hives on and off for more than half a year, and her stomach was often bloated and acid refluxed. She had a gastroscopy and an immune check, but no problems were found. Finally, a food challenge test was performed and it was discovered that she was allergic to eggs. She was confused on the spot and said that I have been eating eggs since I have been eating eggs, and I have never felt uncomfortable immediately after eating them? In fact, her allergic reactions usually only appeared 12 to 24 hours after eating. She either woke up with a rash on her face the next day, or she ate scrambled eggs in the afternoon and started to have bloating in the evening. It was so long ago that it was difficult to connect the discomfort with eating eggs. Most of this delayed type allergy is non-IgE mediated. The onset time may be from a few hours to 72 hours after eating, and the symptoms are more subtle. Skin rash, chronic diarrhea, repeated nasal congestion, and inexplicable fatigue may be its manifestations. Many people treat it as other problems and it takes a long time to find the root cause.

Of course, there are still different opinions on the time definition of delayed-type allergy in the academic circles. Some scholars believe that discomfort that occurs more than 72 hours is more likely to be food intolerance and does not belong to the category of immune-mediated allergies. Some clinicians will also include chronic discomfort that is repeated and fixed with a certain food into the scope of food allergy screening. After all, individual differences are too great, and it is really impossible to use a unified time frame to classify all cases.

Everyone should really not be bound by the stereotype that "allergies must attack immediately". If you always feel unexplainable discomfort every time you eat something, whether it is a few hours or a day or two, you can pay more attention, keep a food diary, and find a professional allergist for investigation. Don't just ignore the food you eat and lack nutrients, and don't ignore it and make it a chronic problem.