5 doctors weighed in:

At 11months my son was immunized for h1n1. Two days later he had an anaphylactic reaction to peanut. Coincidence or cause. There is no family hx.?

5 doctors weighed in
Dr. Steven Machtinger
Internal Medicine - Allergy & Immunology
2 doctors agree

In brief: Coincidence

Anaphylactic reactions require previous exposure and the production of antibodies against the allergen (in this case peanut).
This process takes at least one week and usually two weeks. Your son was already sensitized when he received his h1n1 vaccine and was just waiting for a second exposure to peanut. Initial exposure may have been peanut in breast milk.

In brief: Coincidence

Anaphylactic reactions require previous exposure and the production of antibodies against the allergen (in this case peanut).
This process takes at least one week and usually two weeks. Your son was already sensitized when he received his h1n1 vaccine and was just waiting for a second exposure to peanut. Initial exposure may have been peanut in breast milk.
Dr. Steven Machtinger
Dr. Steven Machtinger
Thank
Dr. Mark Diamond
Pediatrics
1 doctor agrees

In brief: Probable coincidence

I have never read of, seen a patient with, or been told by a colleague of such an occurance.
Highly unlikely causation.

In brief: Probable coincidence

I have never read of, seen a patient with, or been told by a colleague of such an occurance.
Highly unlikely causation.
Dr. Mark Diamond
Dr. Mark Diamond
Thank
Dr. Edward Neilsen
Family Medicine
1 doctor agrees

In brief: Coincidence

Flu vaccine contains no peanut products.
However, immunizations "gear up" the immune system. At least theoretically, a person is more prone to allergic reactions when the immune system is flared-up. For example, skin allergies often flare-up when nasal allerges are also flaring.

In brief: Coincidence

Flu vaccine contains no peanut products.
However, immunizations "gear up" the immune system. At least theoretically, a person is more prone to allergic reactions when the immune system is flared-up. For example, skin allergies often flare-up when nasal allerges are also flaring.
Dr. Edward Neilsen
Dr. Edward Neilsen
Thank
Get help from a real doctor now
Dr. Cindy Juster
Board Certified, Pediatrics
32 years in practice
2M people helped
Continue
108,000 doctors available
Read more answers from doctors