In the one of the most comprehensive studies of drug allergy ever conducted – the Boston Collaborative Drug Surveillance Program – doctors collected data from patients in ten hospitals in the United States, plus eight foreign hospitals, covering 22,227 people in all.

The result present in Drugs that commonly cause allergic skin reactions, show which drugs most often cause skin reactions (itching, rashes, hives and so on). It's important to note that women reached 50 percent more frequently than men, and that the severity of a person’s illness had no bearing on how likely he or she was to react.

What follows is a rundown of the most troublesome drugs. Penicillin. This is not one drug but a general name for a group of antibiotics. Different types of penicillin, made from special molds, control specific types of bacteria infections – making penicillin's the most useful and widely prescribed drugs in the world.

Doctors find, however, that from 1 to 10 percent of the population is allergic to penicillin. Fortunately, most reactions are mild. The chance of a dramatic, explosive reaction is relatively remote; the odds are somewhere between 1 and 4 in 10,000. even then, only 2 in 100,000 of these result in death.

The remainder are kept in check by emergency medical action (strangely enough, people who are allergic to penicillin molds, such as those sometimes found in cheese or around the house, can generally tolerate penicillin).

Doctors have begun to realize that many people who think they're allergic to penicillin aren’t really allergic to it after all. Penicillin allergy, it seems, often fades with time if the drug is avoided. Researches at the clinical Research Center at Massachusetts Institute of Technology, for instance, tested 300 children who were reputedly allergic to penicillin, to find only 19 percent were indeed allergic.

The authors conclude that the incidence of penicillin allergy is over estimated, and that the allergy is not necessarily permanent (Archives of Disease in Childhood, vol. 55, no. 857, 1980). In a similar study, a team of two doctors and a nurse tested 19 children who had been judge allergic to penicillin three to five years earlier and found only 5 were still allergic (Journal of Allergy and Clinical Immunology, September, 1981).

These studies don't mean you should throw caution to the wind and disregard any bad experience you may have had within penicillin. On the contrary: it's important to know if you have an authentic, active allergy to penicillin. Certain conditions – for example, serious infections, a chronic disease such as cystic fibrosis or venereal disease – depend heavily on penicillin for their medical management.

In such cases, doctors conduct a skin test with benzylpenicilloyl-polylysine (called Pre-Pen), which they consider to be the most accurate, lowest risk predictor available for penicillin allergy. Sometimes a doctor can manage penicillin allergy but giving stepped doses of penicillin to desensitize an individual to the drug. If using penicillin is out of the question, the doctor will look for a sale substitute.

Aspirin. Aspirin is the commonly used name for acetylsalicylic acid (ASA). Although aspirin didn’t show up in the Boston study of allergic skin reactions, aspirin and related compounds are the second most likely drugs to trigger allergy. Aspirin allergy (which, for some unknown reason, most often affects women) commonly afflicts the skin, resulting in hives.

Until a few years ago, many doctors thought that nasal polyps were also a hallmark of aspirin allergy. Now, however, many doctors believe that’s not so. Aspirin does seem to produce asthma, though: one out of five asthmatics has aspirin to blame. Your airways tighten up. You wheeze heavily. Your nose continues to run like a broken faucet. And quite often your skin reddens and you suffer giant, puffy hives.

But the lungs and nose don’t have exclusive rights to aspirin allergy. Occasionally, aspirin sensitive individuals experience intestinal cramps or other abdominal discomfort, diarrhea and vomiting. A few experience tremors, rapid heartbeat, constipation – even headaches. But runny nose, asthma and hives are the most common reactions, and the pattern is fairly predictable.

Aspirin allergy does not necessarily occur alone. In one study, 76 percent of people allergic to aspirin were also sensitive to inhalants (such as pollen and dust), 74 percent were allergic to some sort of food and 43 percent were allergic to other drugs (Annals of Allergy, March, 1981).

As a matter of fact, it's quite common for allergy to aspirin to be accompanied by allergy to other pain relievers (analgesics), such as those listed in Drugs that commonly cause allergic skin reactions (these dual allergies are called ”cross reactions.”) If you really need a pain reliever acetaminophen (Tylenol, Tempra, Atasol).

Chemically unrelated to aspirin, acetaminophen can usually be substituted safely, according to Harsha V. Dehejia, M.D., author of The Allergy Book (Van Nostrand Reinhold, 1981). As we mentioned in Rotary Diets, FD&C Yellow No. 5, tartrazine, often causes serious problems in people who are allergic to aspirin. The two compounds seem to cross react. To help you avoid tartrazine,

By law, drugs that contain tartrazine must list on the label. People allergic to aspirin and aspirin compounds may also be allergic to certain foods containing natural salicylates (which have also been linked to hyperactivity). These foods include apricots, berries, cherries, cucumbers, currants, grapes, nectarines, peaches, plums and tomatoes.

Children are not exempt from aspirin allergy. Cecil Collins Williams, M.D., and a colleague tell of four children with poorly controlled asthma who began to wheeze within half an hour after taking aspirin. ”When (aspirin) compounds were removed from their diet, there was a dramatic improvement in their asthma,” write the doctors (Annals of Allergy, abstract no. 1, 1981).

Aspirin shows up in a variety of over the counter remedies for headache pain, menstrual discomfort, sinusitis, backaches, stomach upsets and other aches and pains. Read all the labels of over the counter products if you are allergic to aspirin. And quiz your dentist about any treatments you receive; some dentists insert aspirin containing wicks into tooth sockets during dental repair work.

Vaccines. Flu shots, made from influenza virus cultures on egg, provoke a reaction in anyone who is highly allergic to eggs. Although these vaccines are highly purified, traces of egg occasionally cling to the virus. For this reason, authorities at the national Centers for Disease Control in Atlanta say that people who are highly allergic to eggs shouldn’t receive flu shots.

That applies to people who, when they eat eggs, develop swollen lips or tongue, have dramatic breathing difficulties or collapse in shock. Insulin. During the first few week of insulin therapy, many diabetics experience a slight skin irritation at the site of the injection that usually subsides in a matter of time.

Some diabetics, however, experience larger, more troublesome reactions that never let up. The injection site can be itchy, watery or painful to touch. Worse, the person may feel sick or go anaphylactic shock.

Insulin is made from extracts of either beef or pork pancreas, so if a diabetics seems to be allergic to insulin from one animal, doctors may test insulin's from the other. If that doesn’t do the trick, some diabetics are able to control the disease by eating a carefully planned diet or by using less powerful drugs that are taken by mouth, or doing both.