When to Worry About Fatigue

When to Worry About Fatigue

Q: I have been quite fatigued over the past two weeks. I don’t have any other symptoms. How long should I wait before seeing a doctor about my fatigue?

A: That’s a great question, but one that does not have a scientific answer.

We all go through periods when our energy level is down. It might last a few days, but most often we bounce back after slowing down a bit and getting a good night’s sleep. Even a week or two of feeling more tired than usual is not uncommon.

Fatigue is a relative term, meaning each of us evaluate our current energy level based upon how we feel most of the time. For example, people who are very energetic and go nonstop from early morning to late at night might say they have fatigue if they felt like most of us do every day.

Despite that variation, most people do have a sense when their level of fatigue feels like something more than just being tired. If that’s case, even if it lasted only seven to 10 days, it’s time to call your doctor’s office.

Signs that your fatigue might be related to an underlying illness or infection include low grade fever, night sweats, shortness of breath or loss of appetite. Other triggers for calling your doctor might be waking up exhausted despite a good night’s sleep, not feeling motivated to begin the day, or struggling to do activities that are usually easy for you.

When I see patients with a primary complaint of fatigue who have no other symptoms and a normal physical exam, I usually don’t find a specific cause. And they usually get better on their own.

I may order some simple blood tests to rule out problems such as anemia, an underactive thyroid (hypothyroidism), liver inflammation (hepatitis), or abnormal electrolytes (blood chemistries). I also consider whether the fatigue is related to medication, depression, anxiety or sleep apnea.

If none of these queries provide a diagnosis, I am not surprised when a patient asks me “Then why I am so tired?” Honestly, I won’t have an immediate answer. I speculate whether it could be a low grade viral infection, but have no proof.

Although it’s not very satisfying to my patients or me, I tell them that in great majority of these situations, the fatigue resolves on its own. The important message I leave with them is to continue to call me if their energy level is not picking up.

(Howard LeWine, M.D., is an internist at Brigham and Women’s Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)