Browsed by
Tag: allergy

Dear Doc: Penicillin/Cephalosporin — cross-reactive?

Dear Doc: Penicillin/Cephalosporin — cross-reactive?

Dear Dr. K: I’m allergic to penicillin but my pharmacist has also labeled me cephalosporin-allergic. I’ve never taken cephalosporin. Should I follow her advice?

I can’t give you an answer with a 100 percent surety, but I can come close. As luck would have it, Kaiser Permanent Health Care just finished a research project on cephalosporin allergy.

Their study included 820,000 patients who received a total of 1.4-million courses of cephalosporin (often prescribed as Keflex). Of these, 66,000 were allergic to penicillin. Only one-half a percent of the 820,000 had an allergy to cephalosporin.

The reason your pharmacy warns of a possible cross-reactivity is that penicillins and cephalosporins share a common structural feature called the Beta-lactam ring. The thing that distinguishes penicillins from cephalosporins are side-chain molecules that attach to the Beta-lactam ring. Luckily, most allergy to penicillin is directed against the side chain and not the ring structure. Hence, there would not be cross-reactivity.

The Kaiser Permanent researchers felt that since the potential for cross-reactivity is so low, penicillin-allergic individuals can go ahead and take cephalosporins in most cases. They did advise members of this group who have had anaphylaxis to consider antibiotic testing prior to receiving cephalosporins. (Also, see first item in Q-Tips this issue.)

Dear Doc: Weather, temperature on allergy list?

Dear Doc: Weather, temperature on allergy list?


Dear Doc: I came to see you for a severe spring tree pollen allergy. Those symptoms are much better with my allergy shots; however, I seem to be bothered a lot by physical stimuli such as weather fronts and temperature changes. Is this also allergy?

The unequivocal answer to your question is yes – and no.

Let’s start with what is well-known about allergy. We know it is an immune response to exposure to a protein molecule, such as oak pollen, which causes your spring symptoms. The presence of oak pollen leads to release of allergic molecules such as histamines that mediate typical allergic symptoms.

Of course, there is no foreign protein involved with physical stimuli, but rather a change in barometric pressure, temperature or humidity. Effects of these stimuli actually are neuronal-based symptoms of allergy. Believe it or not, the nerves of our nervous system can cause or contribute to myriad symptoms, including: red/itchy eyes, sneezing, nasal congestion, runny nose, cough, wheeze, airway mucus, GI symptoms and itchy, red, swollen skin.

The process involved: These chemical mediators, such as histamine, also stimulate the sensory nerves. These nerves carry a signal to the brain causing outgoing responses that trigger the sinus congestion and extra-nasal mucus that you experience from the weather change.

Non-allergic individuals can experience modest neuronal responses to physical stimuli, but allergic individuals are much more severely buffeted by a given stimulus. Reason: the sensory nerve input “up-regulates” the central nervous system’s outgoing response, making it much stronger than it otherwise should be.

These neuronal-based issues are currently under intense scrutiny in an attempt to “down-regulate” the sensory feedback and, thereby, lessen symptoms.

Food choices vs. kids’ allergy/asthma:

Food choices vs. kids’ allergy/asthma:

The British Medical Journal recently published the results of a huge international study on allergy termed ISAAC (International Study of Allergies and Asthma in Children). The study was undertaken to evaluate the effects of dietary choices on asthma and allergy. The findings were rather startling.

Basically, a healthy diet prevented problems and an unhealthy diet led to problems. There was a very strong preventive benefit from regular consumption of fruits and green vegetables. Both are a rich source of antioxidants which are known to have a beneficial effect on the immune system. Regular fish consumption was also associated with lower incidence of allergy and asthma.

On the other hand, diets rich in fat led to allergy and asthma. Especially bad in this regard were fast foods such as burgers, fries and sodas. Saturated fatty acids destabilize the immune system, whereas N-3-polyunsaturated fatty acids (found in fish) have natural anti-inflammatory properties.  

The investigators concluded that the “Mediterranean diet” is a model diet for general and allergic health. The Mediterranean diet is high in fruits, vegetables, fish, olive oil, tomatoes, grape/raisin products, and nuts.