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Drug Allergy Quiz

Adverse reactions are common with any drug use. These reactions are often, but incorrectly, called drug allergies and recorded in the medical record as "allergies." A drug allergy is a reproducible reaction mediated through the immune system. One type of allergy can be caused by a blood protein called IgE or the allergy antibody. The usual reaction associated with IgE is a type of a rash called hives or urticaria, where itchy spots come and go and never stay in the same place for more than one day. Rarely, a systemic shock-like reaction called anaphylaxis can occur with IgE-mediated allergy. IgE-mediated drug allergy can often be safely identified by skin testing when available, for very specific drugs, or drug challenge for most other drugs. Another common immunologically-mediated reproducible drug hypersensitivity is a delayed onset rash caused by an immune cell called a T-cell. These reactions commonly occur within five days of starting a drug. These reactions typically are total body rashes, but the spots that make up these rashes last longer than hives, usually days to weeks. Only a very small minority of reported adverse drug reactions are true drug allergies (caused by the immune system). There are however, many other reasons people have allergy-like reactions when taking medications, so even patients with a very good history often have negative allergy testing and can safely use the implicated drug when needed.

Question 1
If you have an unconfirmed penicillin allergy, the safest way to proceed is
a. Avoid all antibiotics
b. Avoid all penicillins and cephalosporins
c. Get evaluated and tested for penicillin allergy

Answer is c. Most adverse drug reactions have other causes, and many do not recur with re-exposure. Penicillin is the most common drug suspected of causing hypersensitivity, but less than 5% of individuals tested for penicillin allergy are positive. Penicillins do not significantly cross react with cephalosporins (another type of antibiotic) although antibiotics used in place of penicillins in patients with reported penicillin allergy may carry a higher risk of side effects. Penicillin allergy testing is very safe.

Question 2
Suspected severe IgE-mediated penicillin allergy can be safely confirmed or refuted by
a. Blood testing
b. Skin testing, followed by an oral challenge if skin test is negative
c. History alone

Answer is b. Blood testing for penicillin allergy is very inaccurate. History can be helpful, but testing is needed to confirm a true allergy. Even with a very strong history of penicillin-associated anaphylaxis, many individuals will be penicillin allergy test negative, particularly if the reaction occurred more than 10 years ago.

Question 3
Individuals with questionable, but low-risk, history of a specific drug allergy can be safely evaluated by
a. Skin testing
b. Blood testing
c. Re-challenge, in which the drug is reintroduced in a monitored setting

Answer is c. For most drugs, there are no reliable skin tests, or the drugs are directly irritating when injected into the skin. There are very few reliable blood tests for allergy, but some medically associated materials, such as latex, can be tested by commercially available blood allergy tests. Re-challenge remain the most valuable tool to determine if a patient is able to take a medication again.

Question 4
For individuals with hives immediately with exposure to radiocontrast or a delayed onset rash within a week of exposure to radiocontrast, the safest way to have future studies with radiocontrast is to
a. Avoid all radiocontrast
b. Avoid all iodine
c. Determine exactly what type of radiocontrast caused the reaction and use any other new-style, non- or low-ionic, radiocontrast now available
d. Get premedication before all future radiocontrast use

Answer is c. Skin testing to different radiocontrast agents is one means of determining reactivity to different agents but is not readily available and non- or low-ionic agents are associated with fewer reactions. Premedication may still be required in select cases.

Question 5
If someone requires a radiologic study with contrast but has a history of shellfish or iodine allergy they should
a. Receive radiocontrast without concern
b. Avoid all radiologic studies involving radiocontrast
c. Undergo evaluation for shellfish food allergy before undergoing the radiologic study
d. Receive steroids and antihistamines before receiving contrast

Answer is a. There is no increased risk of radiocontrast hypersensitivity in patients with a history of shellfish food allergy. It is not possible to have iodine hypersensitivity.

Question 6
If a patient experiences a reaction such as hives, nausea, and/or constipation associated with an opiate, such as codeine, hydrocodone or morphine, it is likely to be a life-threatening allergy and all opiates should be avoided.

False. Hives, itching, nausea, brain fog and constipation are all common and expected reactions associated with all opiate use because of the specific opiate receptors present in different parts of the body. Any opiate can still be used in the future when needed and lowering the dose or using other medications to help treat the opiate side effects can be helpful.

Question 7
It is common for patients to experience reactions to the inactive ingredients in medications, such as fillers and dyes.

False. It is rare for patients to be allergic to the inactive ingredients in medications, and much more common for patients to experience reactions to the active medication ingredient or to experience symptoms that are coincidental with medication usage.

Question 8
Patients who have experienced dizziness and lightheadedness while receiving a local anesthetic at the dentist should do which of the following:
a. Use general anesthesia for all procedures
b. Undergo testing and/or challenge to the local anesthetic
c. Avoid local anesthetics for life

Answer is b. Local anesthetic allergy is quite rare, but patients may experience symptoms related to anxiety surrounding procedures requiring the use of local anesthetics. They also may experience mild side effects from the use of epinephrine in the local anesthetic. Skin testing and challenge may be done at an allergist's office so that patients may undergo future needed procedures comfortably with a local anesthetic.

Question 9
Occurrence of only diarrhea and abdominal pain after taking antibiotics like amoxicillin is a sure sign of a drug allergy?

False. Gastrointestinal upset is a common side effect of antibiotics and some other medications. Side effects can occur in anybody who takes medications. If symptoms are intolerable other drugs can usually be used.

Question 10
Patients who report severe immediate allergic drug reactions or anaphylaxis can never receive the same drug in future.

False. Usually it will not be safe to use the same drug. However, in the event the drug is absolutely necessary, and no other effective drug choice is available, the allergist can safely introduce the drug in very small amounts with gradual increasing doses in a closely monitored setting. This is called drug desensitization or temporary induction of drug tolerance.

You answered   questions correctly.


Most adverse reactions associated with other antibiotics, opiates, other pain pills, blood pressure medications, cholesterol medications and other commonly used drugs are also not immunologically-mediated drug hypersensitivity or allergy but have other reasons for occurring. Second choice medications may be less effective. Consultation with an allergist, and testing or rechallenge if needed, can ensure that the safest drug is used.