Mystery Diagnosis: Bad Taste in the Mouth

Learn how doctors figure out what’s happening when patients have strange symptoms.

Rob Lamberts, MD,
October 5, 2010
Episode #066

It’s time for another “Mystery Diagnosis” article. So far, I’ve covered mystery coughs and dizziness. Both are fairly common things for me to see in the office, and both are things I was taught to evaluate. But what happens when a person comes in with something strange?

Mystery Diagnosis: Bad Taste in the Mouth

This week’s topic actually comes from Richard, one of my Quick and Dirty Tips bosses, who wondered what could cause a bad metallic taste in the mouth. 

Hmm...well, I must have slept through that “metallic taste in the mouth” lecture in medical school. Unfortunately my patients are a lot like Richard--not polite enough to have symptoms that follow the textbooks. It’s actually stuff like this that makes my job challenging.

So how do you approach this kind of strange symptom? The same way you approach any medical problem: systematically. In my previous medical mystery articles I stressed the importance of a disciplined and detailed approach to any problem—even the common ones. For unusual complaints in particular, the detailed approach gives the most information to help unravel the mystery.

Step 1: The History

The first step in the diagnosing process is to take a history of the problem itself. It’s time to ask the what, when, where, how long, and how bad questions? In this case, Richard (who is now a fictional patient, not my boss) says that the symptom started two days ago when he woke up with a bad taste in his mouth; and the bad taste has stayed with him through the day, although it seems to improve over time. The bad taste is very annoying, but not at all painful. He’s never had symptoms similar to this. He tried brushing his teeth and using mouthwash, but that didn’t make it any better.

More Questions About the Symptom

In asking more questions, another interesting fact came out: the night before he first experienced the symptom, Richard went out to eat with a friend--and they both awoke with the same funny taste in their mouths. What did they eat? He told me he had eaten tapas, which I learned (being the backwater Southerner that I am) is a Spanish food consisting of small portions of different dishes--kind of like appetizers. The temptation here is to jump to the obvious conclusion: something in the tapas is the culprit. After all, it would be a major coincidence for both people to have the same symptom at once. It’s tempting, but good medicine is always thorough.

What are the Supporting Facts?

So now I move on to the supporting facts around these symptoms. The review of systems--when I ask the patient a bunch of questions about any other symptoms he may be having--is the next bit of information I gather. Richard has not been having any fever, fatigue, or body aches. He feels pretty good overall. The only other symptom he’s been having is a cough that has gone on for several weeks, as well as some runny nose and sore throat in the morning (which he attributes to allergies). 

He’s not taking any medications at the present time, and has no significant medical problems. 

The Examination

There is an important rule I use in making diagnoses: uncommon presentations of common things are far more common than uncommon things.

The physical exam is largely focused on the area of his complaint--the mouth--but I do look at other areas for completeness’ sake. His temperature and blood pressure are fine, but he has gained about ten pounds since his last visit. His mouth exam shows good teeth, with no tooth decay or other evidence of infection, and he seems to be making plenty of saliva. His breath doesn’t seem to smell particularly bad either (thank goodness). As unpleasant as it seems, I do have to use whatever senses I can to make a diagnosis, and bad breath is a possible clue to the cause of this strange taste in his mouth.

The Differential Diagnosis

My differential diagnosis--the list of possible causes of his symptoms--is as follows:

Food: Something in the food he ate last night is my leading candidate. If he ate fish, there are some possible toxins that could cause a funny taste, including heavy metals such as mercury, which can be present in fish.

Medications: Medications are the most common cause of  a bad taste in your mouth. Lunesta, a popular sleep medication, has it as one of the major side effects, as does the antibiotic clarithromycin, also known as Biaxin. Richard denies taking any medications in the past few days, including over-the-counter medications.

Conditions: Having a dry mouth can also alter taste. Certain medical conditions and medications can decrease the saliva production, leading to a dry mouth. Something as simple as a stuffy nose that then caused Richard to sleep with his mouth open (making it dry) could cause him to wake up with a funny taste in his mouth. Reflux can’t be dismissed either, although it would be odd that both Richard and his eating companion started having reflux on the same day. Without that bit of information, reflux would be my leading candidate, since he’s gained weight recently, and is having sore throat and cough (both of which are possible symptoms of reflux).

There is an important rule I use in making diagnoses: uncommon presentations of common things are far more common than uncommon things. It’s far more common to see an odd presentation of reflux than it is to see bonefish poisoning (which is on the list, it turns out).

I want to point out that in this circumstance I would probably use a medical reference in the exam room to figure out possible causes of the bad taste. I don’t know everything, and pretending I do to win points with patients only leads to trouble. A sign of a good doctor is that he freely admits when he doesn’t know something and works to find out the answers.

The Plan

So what do I tell Richard? Since the symptoms just started two days ago, I am inclined to wait and see if the symptom goes away on its own. If it was something in the food, it will likely go away (as long as he stays away from those fancy-schmancy Spanish foods for a while). If the symptom doesn’t go away, I would probably put him on a stomach acid blocker and see if this made his symptom go away.

When I checked with fictional Richard a few days later, he was happy to report the bad metallic taste went away for good.

If you have topics that you want me to cover, send them to housecalldoctor@quickanddirtytips.com, or you can submit them to me on twitter (@housecalldoc) or my Facebook page.

Let me once again remind you that this podcast is for informational purposes only. My goal is to add to your medical knowledge and translate some of the weird medical stuff you hear, so when you do go to your doctor, your visits will be more fruitful. I don’t intend to replace your doctor; he or she is the one you should always consult about your own medical condition.

Catch you next time! Stay Healthy!

Mouth image courtesy of Shutterstock