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Allergic to a Drug or Vaccine?

Read on to learn the difference between being allergic to a drug or vaccine.

Your Local Health | Written by BJ Towe

At The Iowa Clinic, Jennifer Petts, D.O., says you may not be allergic after all. She explains why it's important to find out for sure. If you or a loved one has ever had a bad reaction to a drug or vaccine, you may believe it was due to an allergy — and maybe it was. But most reactions aren't actually caused by the drug or vaccine. And avoiding it could mean you, your child, or another loved one might not receive the most effective medical care or treatment when it's needed most.

Only 1 In 10,000 People Have Severe Penicillin Allergies

Dr. Petts, an Allergist/Immunologist with The Iowa Clinic, says, “Penicillin allergies are the top reported drug allergy, but only about one out of 10,000 people have a severe reaction to IV-administered penicillin.” A severe allergic reaction involves whole-body, life-threatening symptoms that appear within an hour of exposure. Called anaphylaxis, symptoms can include pain in the stomach or chest; swelling of the face, eyes, or tongue; heart palpitations; skin turning blue; slurred speech; wheezing; and unconsciousness. Anaphylaxis requires immediate medical treatment.

According to an article appearing in the New York Times, “About one in 10 Americans reports a serious allergy to the antibiotic penicillin or any of several closely related drugs. Yet in about 90 percent of cases, no serious allergy exists.”

Petts Says There are a Number of Reason so Many People’s Medical Records Erroneously List Penicillin Allergy

  • They may have had an adverse reaction such as diarrhea, which is predictable and can affect anyone based on the dose and prior exposure to the antibiotic.
  • Some older adults who reacted badly to penicillin in the 1960s actually reacted to impurities in the drug. Today's manufacturing techniques for penicillin have greatly improved.
  • After 10 years, even people with true penicillin allergies typically outgrow it.

“For many infections, penicillin is hands down the most effective treatment available,” says Petts. “Alternatives are more expensive and can have adverse effects, such as destroying beneficial organisms in the intestines or resulting in kidney or liver injury. For some infections, it's the only effective treatment.”Additionally, before having surgery, many medical providers now require individuals who believe they have a penicillin allergy to first get skin prick testing (see below), which provides conclusive allergy results. Petts says, “If you can receive penicillin, that not only reduces the risk of potential complications, but it also reduces the cost.”

In an emergency, patients with true penicillin allergies can be “taught” to tolerate it. When a patient with a penicillin allergy is critically infected, Dr. Petts says drug desensitization can prepare the patient to receive full doses of the essential antibiotic. “We can trick their bodies into accepting the antibiotic,” says Petts. This is achieved by reintroducing very small, tolerable doses of the allergen into the patient's system every 15 to 30 minutes using a little higher dosage each time. “Because of the potential side effects, this requires constant monitoring in the hospital's intensive care unit, but — when a patient really needs a certain antibiotic — desensitization makes it possible,” says Petts. After a patient stops taking the antibiotic, it cannot be administered again without first repeating the desensitization process in the ICU.

Allergic Reactions to Vaccines are Rare

Immunizations have been called the single-most important contributor to our nation's health. Still, too many hildren and adults are not immunized against some of the worst diseases — polio, mumps, German measles, smallpox, whooping cough, chickenpox, and tetanus, for example. This is usually because they falsely believe they are allergic to the vaccine.“By far, the majority of people can safely receive vaccinations,” says Petts, who explains how this is possible — even when an allergic reaction has occurred in the past.

  • People are allergic to a component used in manufacturing the vaccine, not to the vaccine itself. Common ingredients used in the development or delivery of the vaccine include yeast, alum, gelatin, or latex. “After we identify what caused the reaction, we can often find the vaccine from a manufacturer that does not use the offending allergen, making it completely safe for our patients,” Petts says.
  • Eggs aren't the problem once believed. “We now know that individuals with egg allergies can safely receive the influenza vaccine as long as they are monitored,” Petts says. “This is huge in terms of preventing influenza outbreaks and deaths among vulnerable populations such as young children, older adults, and those with immune eficiencies.”

Without immunizations, people are not only at greater risk for contracting a host of terrible diseases, but they are also likely to have more visits to emergency rooms, more hospital stays, and more medical bills. “For example, people who never get a tetanus shot will, at some point, get stuck by something rusty. To avoid a potentially deadly infection of the nervous system, they'll need to go to the emergency room to receive a special medication — and not all ERs keep it on hand,” says Petts. “That can be a very dangerous situation.”For a list of legitimate reasons people should not receive vaccines, visit

Know for Sure - Get a Skin Test

Finding out whether or not you have an allergy is easy with a skin prick test, which is often followed by intradermal testing. These safe tests are effective in pinpointing specific allergies. ALLERGIES Your healthcare provider will place a small amount of a substance on your skin and then lightly prick the skin, which allows the allergen to get under the skin's surface. If an allergy is present, swelling, redness, or other signs of a reaction will typically occur within 20 minutes.“For patients who have had a concerning reaction to a form of penicillin, but whose skin tests are negative, we can do an oral challenge to confirm that the patient can safely receive the drug,” says Dr. Petts.

An oral challenge involves giving a patient a full dose of the antibiotic. Petts says, “The patient then stays in our office for two hours. Since severe reactions typically occur within 30 minutes, we are right there and ready to treat them. ” For individuals who suspect drug or vaccine allergies, Petts emphasizes that it's well worth the time it takes to get a skin test. After all, finding out that you might not be allergic to that drug or vaccine could save your life.

To schedule a skin test, call The Iowa Clinic at 515.875.9450.

The Pennicillin of Drugs

There are several varieties of penicillin, each targeting different types of infections. These include:

  • Amoxicillin
  • Ampicillin
  • Dicloxacillin
  • Oxacillin
  • Penicillin V
  • Peracillin
  • Zosyn
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