The Curbsiders podcast

#215 Medical Myths: Challenge Dogma with Dr. Douglas Paauw

May 25, 2020 | By

Drink on metronidazole, take expired meds, and inject epinephrine in extremities. 

Chase that metronidazole with a beer! Pop some 30 year old pills! Retrain your brain as our esteemed guest Dr. Douglas Paauw goes over his popular annual ACP presentation on Medical Myths. Learn about how some common medical myths originate and continue in our practice. We discuss why it’s okay to drink on metronidazole, take expired medications, inject epinephrine into extremities and why recurrent sinusitis may not really exist.

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Written and Produced by: Justin Berk, MD MPH MBA

Infographic and Cover Art: Beth Garbitelli

Hosts: Justin Berk, MD, MPH, MBA; Matthew Watto MD, FACP; Paul Williams MD, FACP   

Editor: Emi Okamoto MD (written materials); Clair Morgan of

Guest: Douglas Paauw, MD


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Time Stamps

  • 00:00 Intro, disclaimer, guest bio
  • 02:22 Guest one-liner; Career Advice, Picks of the Week*: Being Mortal, book by Atul Gawande; The Band Played On, book by Randy Shilts; Lagunitas Hoppy Refresher: zero alcohol, zero calories!
  • 06:15 Medical Myth Definitions
  • 10:20 Dogma: Metronidazole and Alcohol; Healthy RCT Metronidazole and Alcohol
  • 19:09 Expired Medications; Military Stockpiling Study
  • 24:22 Aspirin and Nitroglycerin; Unopened eye drops; Epi-Pens; Expired Med Recap
  • 31:13 Sinus Headaches; Trigeminal Nerve; Pearl: Recurrent headaches; Study showing Effectiveness of treatment (92%)
  • 41:07 Epinephrine in extremity; RCT of Epi in Extremities
  • Study showing Experts use it; Podiatry journal
  • 48:39 Take home points and Outro

Medical Myths: Pearls

  1. Medical myths are practices accepted as dogma despite a lack of evidence.
  2. Medical myths often occur because the physiology seems simple, case reports are extrapolated, or tradition prevents the thought of challenging dogma.
  3. In healthy individuals, metronidazole does not seem to cause any disulfiram-like reaction with alcohol
  4. Many as-needed medications do not lose potency over time.
  5. Recurrent sinusitis / sinus headaches are often migraine headaches that respond to triptans
  6. Epinephrine can be safely injected into extremities for injury repair
A descriptive chart summarizing the medical myths discussed in the podcast.

Medical Myths: Notes 

Dr. Pauuw’s best advice: Don’t try to look good. Be good.

What is a Medical Myth

“Medical myths” are practices that are accepted as dogma but lack evidence. They occur:

  1. Because the physiology makes sense; It’s easy to learn but may not be so simple.
  2. Case reports are extrapolated to become dogma even though they have much less scruinity than higher levels of evidence
  3. Tradition – this is how it’s been since the beginning of medicine.

Paul also suggests perhaps they just align with a good mnemonic.

Metronidazole and Alcohol

While there is a warning label on metronidazole, there is no strong evidence to avoid alcohol.

In 1950, there was a thought that metronidazole had a disulfiram-like reaction. Studies disproved this but were mostly ignored. A review of case reports documented emesis from people that had been drinking and taking metronidazole (Williams, 2000). But there was no evidence for the reaction.

In rat models, there is no inhibition of aldehyde dehydrogenase. But acetaldehyde levels did increase in the GI tract which perhaps could make prone persons more likely to have diarrhea or side effects.

In 2000, a randomized controlled trial of 12 healthy volunteers (medical students) received metronidazole or placebo for five days then ethanol,  and there was no difference in symptoms or acetaldehyde levels between groups (Visapaa, 2002)

Dr. Paauw Expert Opinion: “And that is all of the world’s literature on the interaction between metronidazole and alcohol.” Rumors suggest the next CDC STI guidelines will remove the metronidazole warning. 

Expired Medications

Research from the US military suggests that many medications can be around for a very long time (Lyon, 2006).  In one study of 122 different medications, almost all had >90% potency (the FDA requirement) at 1 year beyond expiration (with an average extension to 66 months). This included many antibiotics and painkillers. 

One study of  14 sealed medications that were 28-40 years expired showed 12/ 14 had >90% potency with the exception of aspirin (Cantrell, 2012). Aspirin did break down to <1% potency.  There are no significant toxic side effects either. The classic teaching of expired tetracycline causing Fanconi syndrome was a formulation that was taken off market in the early 1980s.

The studies mentioned related to unopened medications. One study looked at 12-week-expired and opened travoprost eye drops and found them to be equally clinically efficacious as unopened medications (Reis, 2004).

Dr. Paauw fun fact: travoprost eye drops are more valuable than gold by weight

Epinephrine auto-injection devices may also last longer than the expiration date, often labeled 18 months or less from manufacture. A study in Annals of 40 expired pens highlights that most all have a good level of potency at 1 – 2.5 years after expiration (Cantrell, 2017).  

Dr. Paauw Expert Opinion: Don’t toss the expired epinephrine pens but, for now, have them as a back-up only.  Other important medications may also need fresh refills; (we cannot confidently or safely say that all medications never expire), more data is needed for necessary and important medications.

Sinus Headaches 

Recurrent sinus headaches are less likely bacterial sinusitis but actually a variant of migraine headaches. One study of nearly 3000 patients who had self diagnosed or physician-diagnosed “sinus headaches (sinus pressure, sinus pain, nasal congestion), showed 88% met criteria for IHS migraine (80%) or migrainous criteria (8%) (Schreiber, 2004). 

These studies were in 2004-2006, but this has not made mainstream primary care information. One study suggested an 8 year delay in diagnosis of migraine for those with recurrent sinus symptoms (Hashel et al, 2013). 

The pain can affect the trigeminal nerve (i.e. nerves around the sinus) and include bilateral pain (in contrast to typical migraine pain that is thought to be unilateral) (Eross, 2007).

A study on “sinus headaches” showed many of these patients had normal sinus endoscopies and CT scans. Ultimately, migraine-directed therapy like triptans had a 92% effectiveness in treating “sinus headaches.” (Of note, there was an enormous drop out after the diagnosis phase of the study, because individuals did not feel that a migraine cocktail could possibly help.) (Kari, 2009). 

Watto opinion: Be gentle when telling people they don’t have sinusitis. 

Epinephrine in Extremity

Existing dogma states epinephrine in the extremities can cause ischemic necrosis in end-arterial areas. Instead, it may actually help with bleeding. 

In a randomized control trial with 60 procedures (20 years ago), lidocaine with epinephrine was associated with less bleeding and had no more adverse complications (Wilhelmi, 2001). 

In 2005, a study of 9 hand surgeons (3,110 consecutive cases) showed that epinephrine injection was associated with zero finger infarctions. (Lalonde, 2005). Recall in the anaphylaxis episode (Curbsiders #151), even accidental epinephrine pens in fingers have not been associated with necrosis!

A study in the 1970’s showed a podiatrist with over 65,000 surgical procedures using lidocaine with epinephrine and found no complications due to epinephrine. This has been confirmed with a more recent literature review (Ilicki, 2015).

Paul contribution: Check out the first article describing Heyde Syndrome (a 1958 NEJM Correspondence). An excerpt:I have not found any reference to this association in the literature, and thought that a letter to a prominent journal might elicit some response about the matter.”


The cover of Atul Gawande's book 'Being Mortal' and the title image of Roger Spottiswoode's movie 'And the Band Played On' based on Randy Shilts' book of the same name.
  1. Being Mortal, book by Atul Gawande
  2. And the Band Played On, directed by Roger Spottiswoode; book by Randy Shilts
  3. Lagunitas Hoppy Refresher: zero alcohol, zero calories!

*The Curbsiders participates in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising commissions by linking to Amazon. Simply put, if you click on our links and buy something we earn a (very) small commission, yet you don’t pay any extra


  1. Williams et al. Do Ethanol and Metronidazole Interact to Produce a Disulfiram-Like Reaction? Annals of Pharmacotherapy. 2000. []
  2. Visapaa JP et al. Lack of Disulfiram-Like Reaction With Metronidazole and Ethanol. Ann Pharmacother. 2002. [].
  3. Lyon RC et al. Stability profiles of drug products extended beyond labeled expiration dates. J Pharm Sci. 2006 []
  4. Cantrell L et al. Stability of active ingredients in long-expired prescription medications. Arch Intern Med. 2012. []
  5. Reis R et al. Effects of Travoprost 0.004% Ophthalmic Solution, Six Weeks After Its Laminated Packaging Had Been Removed, in Primary Open-Angle Glaucoma. Clin Ther. 2004. []
  6. Cantrell et al. Epinephrine Concentrations in EpiPens After the Expiration Date. Ann Intern Med. 2017 []
  7. Schreiber et al. Prevalence of Migraine in Patients With a History of Self-Reported or Physician-Diagnosed “Sinus” Headache. Arch Intern Med. 2004. [
  8. Al-Hashel et al. Migraine misdiagnosis as a sinusitis, a delay that can last for many years. J Headache and Pain. 2013. []
  9. Eross et al. The Sinus, Allergy and Migraine Study (SAMS). Headache. 2007. []
  10. Kari et al. Treatment of Sinus Headache as Migraine: The Diagnostic Utility of Triptans. The Laryngoscope. 2009. []
  11. Wilhelmi, et al. Do Not Use Epinephrine in Digital Blocks: Myth or Truth? Plast Reconstr Surg. 2001. []
  12. Lalonde, et al. A Multicenter Prospective Study of 3,110 Consecutive Cases of Elective Epinephrine Use in the Fingers and Hand. J Hand Surg Am. 2005. []
  13. Ilicki et al. Safety of Epinephrine in Digital Nerve Blocks: A Literature Review. J Emerg Med. 2015. []


Listeners will challenge the dogma of specific medical practices that have been spread without evidence basis.

Learning objectives

After listening to this episode listeners will…

  1. Counsel patients taking metronidazole on alcohol use
  2. Describe the risks associated with taking expired medications
  3. Diagnose and treat commonly defined “sinus headaches”
  4. Describe the risks associated with epinephrine injections in the extremities 


Dr Paauw reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures. 


Pauuw D, Berk J, Williams PN, Watto MF. “#215 Medical Myths: Challenge Dogma with Dr. Douglas Paauw”. The Curbsiders Internal Medicine Podcast. May 25, 2020.

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