Part 3: Recognizing Red Flags & Outsmarting Killer Foils

If you are preparing to take a BPS exam, then you already know that you need to do more than just memorize medication facts. The BPS exams test your ability to USE your knowledge at an elite level. You must be prepared to prove yourself.

In this series of articles, our experts have pooled their knowledge and experience to tell you how to do just that. In previous articles, we have covered test taking strategies and dissected the question types you will encounter along with key tactics to master them. If you haven't already, be sure to look at Part 1 and Part 2 of this series.

Today, Drs. Busti and Cocchio address red flag medications to keep an eye out for and killer foils that you DO NOT want to get wrong.


What are they?

These are questions that will revolve around a high-risk medication that has a well-known clinical issue or concern related to its use. If you see these medications in a question, stop and look for the related issue. There are typically only a few directions these questions can go, and they are testing your knowledge on a classic concept - like those classic teaching points you would encounter in a residency situation.

Red Flag Example

For example, Amiodarone has been around for a long time and is one of the main antiarrhythmics used in every day clinical practice for both chronic and acute conditions. If you see Amiodarone in a question, you will likely be facing something to do with its extremely long half life. You must know that it has interactions with Digoxin and Warfarin, and will take seemingly forever to adjust related levels in the patient. It can also have side effects of Pulmonary Fibrosis, Hepatotoxicity, QT-Prolongation, ocular toxicities, and skin changes.

This question will likely have you addressing something regarding the type and rate of administration in relation to these things.


What are they?

"Killer foil" refers to a type of question in which two different diagnoses have similar presentations but require different treatments. In these cases, you must be able to identify the differences between diagnoses and adjust accordingly.

Note: while you are not typically responsible for determining the diagnosis in a clinical situation, killer foils are important for you to recognize both for the exam and for clinical application. The board exam states that you are responsible for understanding the pathophysiology of a disease - this content IS testable. You should be able to recognize the clinical signs and symptoms of a disease and be able to start piecing the situation together anytime you are treating a patient. The exams test this because it is required to provide the highest level of care.

While it may not be your primary responsibility to diagnose, if you truly understand how these scenarios coincide, you may be the one to identify the underlying problem or prevent the wrong treatment from being administered for a patient. In many medical situations, the faster a problem is identified, the better the outcome. This is what GOOD medicine looks like, and the standard to which you are being called to work.

Killer Foil Example

A 27-year-old female with no PMH presents with intermittent fever and worsening sore throat for the past 3 days. Upon examination, she has swollen tonsils with some small exudates, lymphadenopathy to the back of the neck and mild left upper quadrant abdominal pain. She denies any drug allergies and was started on amoxicillin based on her exam findings alone. Two days later she calls the clinic nurse and reports a rash all over her body. She denies any shortness of breath, lip or tongue swelling, nausea or vomiting.

In this situation, you would need to recognize that she is not having an allergic reaction to the amoxicillin, but was initially misdiagnosed as having strep when she actually had mononucleosis. The killer foil here is that mononucleosis and strep pharyngitis both present similarly - with a sore throat, fever, and lymphadenopathy. You would treat strep pharyngitis (caused by Group A beta-hemolytic streptococcal bacteria) with an antibiotic, whereas you would only provide supportive care for mononucleosis (which is caused by the epstein barr virus) while it runs its course.


A rash is known to periodically develop when amoxicillin is prescribed to a patient with mononucleosis - not to be mistaken for an allergic reaction. In our example above, the absence of shortness of breath, lip/tongue swelling, or nausea/vomiting, demonstrates that the patient's rash is not indicative of an amoxicillin allergy, and does not require treatment.

Had the initial examiner known the specific differences between these disease presentations, this situation could have been prevented. You, however, will not make this mistake (and may prevent someone else from doing so!), because you now know to look for these simple distinguishing symptoms:

  • Mononucleosis (EBV): lymphadenopathy occurs in the posterior chain, sometimes accompanied by upper left quadrant abdominal pain due to swelling of the spleen 
  • Strep pharyngitis (GABS): lymphadenopathy occurs in the anterior chain

Additional Resources

Check out our FREE webinars on Board Certification & Test-Taking Strategies!

Blog: BPS Test-Taking Strategies Series: Part I

Blog: BPS Test-Taking Strategies Series: Part II

Blog: How Important are Biostatistics & Clinical Literature on BPS Exams?