Penicillin allergy and cheese

January 22, 2003

I have an anaphylactic reaction to Penicillin. It's source from what I can gather is P. chrysogenum and yet I can eat Roquefort cheese whose mould is P. roquefort without so much as a single hive. Both moulds are in the Penicillium family, one completely closed my airway in a hospital ER in 1968 and one doesn't cause a reaction at all. How come? -- Catherine, Canada

Most of the people who have written about a correlation between cheese and penicillin allergy have indicated no problems with eating cheese. However, there appears to be rare situations when eating food with penicillin in it does cause reactions for penicillin-sensitive individuals.

That is why I've shared two questions today. One person indicates a reaction to blue cheese and questions what other products to avoid. The other person questions why her penicillin allergy does not cause a reaction when she eats blue cheese.

Locally, I've not seen any reports of allergic reactions to blue cheese from patients with penicillin allergy.

The literature I was able to find gave rare incidences where penicillin-sensitive individuals had allergic reactions after ingesting milk, beef, pork or chicken that had traces of penicillin in them.

These studies were not extensive, and the conclusion of most of the material I've seen on this is that small amounts of penicillin in food seldom causes an anaphylactic reaction in penicillin-sensitive individuals.

During my 35 years as an R.N., I've worked with a lot of penicillin-sensitive individuals. I've not seen any evidence that penicillin in food caused problems for these people.

Controlled studies are considered more reliable than the experience, however. Unfortunately, there does not appear to be any well-documented extensive studies available on this subject in the literature.

One thing to remember is that a person can have an allergy to penicillin, and a separate allergy to cheese, milk, chicken, pork, beef, or another food substance as well.

One of the items I read pointed out that most serious penicillin allergies are usually to injected penicillin. Since cheese is consumed by mouth, the thinking is that a reaction to it would not likely be as severe.

But this does not mean penicillin by mouth is safe for those with penicillin allergy; nor does it mean that it is safe for all individuals with penicillin allergy to eat blue cheese.

Interestingly, literature does support the fact that individuals with allergy to inhaled mold spores may also have allergic reactions to cheeses, fermented drinks, soy sauce, buttermilk, mushrooms, dried fruits, vinegar, or foods containing yeast.

Conclusion:
Obviously, Doug, who writes above that he gets hives when he eats blue cheese, needs to eliminate blue cheeses from his diet. Probably he should make sure that all cheese is eaten fresh before mold has an opportunity to grow on it, and discard cheese that has any discoloration that might be mold. If he has reactions to any of the foods mentioned in the paragraphs above, or any other foods, he will need to eliminate those also.

Catherine, on the other hand, has not had any indication of sensitivity to roquefort (blue) cheese. One possibility is that Catherine has outgrown her penicillin allergy. Testing to penicillin may be in order. But the more likely conclusion is that Catherine is one of what appears to be the majority penicillin-sensitive individuals who are not affected by small amounts of penicillin in foods.

Always err on the side of caution. Anaphylaxis (severe reaction to penicillin or other allergens) can be fatal. If you are in doubt, do not eat the questionable food. Never take a chance with your life. The best person to consult about what you can safely eat, or what medications you can take, is your personal physician or your allergist.

Bonus: While I was researching this, I found a neat electron microscope photo of penicillium mold growing on cheese, and I wanted to share it with you. Click here to see the photo in a new browser.

A related topic I've written about is
Penicillin and Penicillium Mold Allergy.

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