Fatigue from Mono: What Causes It and How to Manage It

When you have fatigue from mono, an overwhelming, persistent tiredness caused by infectious mononucleosis, often triggered by the Epstein-Barr virus. Also known as glandular fever, this isn’t just a case of being worn out—it’s your immune system fighting a deep, systemic infection that drains your energy reserves. Unlike regular tiredness, this fatigue doesn’t go away with a good night’s sleep. It lingers, sometimes for months, making even simple tasks feel like climbing a hill.

This kind of exhaustion is tied directly to mononucleosis, a viral illness most commonly caused by the Epstein-Barr virus, which infects B cells in the immune system. Once the virus enters your body, your immune system goes into overdrive, producing waves of white blood cells and inflammatory signals. That’s what makes you feel like you’ve been hit by a truck. The virus doesn’t directly destroy your muscles or nerves—it’s the immune response itself that creates the crushing fatigue. And because your body is still cleaning up the aftermath, even after the fever and sore throat fade, the tiredness sticks around.

People often mistake this fatigue for laziness or depression, but it’s biological. Studies show that up to 10% of people with mono still report significant tiredness six months later. It’s not in your head—it’s in your cytokines, your mitochondria, and your nervous system’s reset button being stuck in the ‘off’ position. Epstein-Barr virus, a member of the herpesvirus family that stays dormant in your body after infection can reactivate under stress, which is why some people feel crashes even years later.

What helps? Rest isn’t optional—it’s medicine. Pushing through leads to longer recovery. Hydration, gentle movement like walking, and avoiding alcohol and heavy exercise protect your liver and immune system. There’s no magic pill, but time, patience, and smart pacing make the difference between dragging through the day and slowly getting your energy back. You’re not broken—you’re healing.

Below, you’ll find real, practical insights from people who’ve been there—how they managed the fatigue, what worked, what didn’t, and how to know when it’s time to see a doctor instead of just waiting it out.