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Published on: 7/15/2026

What are possible causes when I have both fatigue and fever but no other symptoms?

Yoshinori Abe

Reviewed by Yoshinori Abe, MD

Internal Medicine

When symptoms appear in isolation without a clear cause, the main disease categories to consider are infectious diseases, cancers, and autoimmune or inflammatory conditions. Each of these categories includes a wide range of illnesses, from common infections to chronic inflammatory disorders and various forms of cancer, making accurate self-assessment difficult.

Because these categories overlap in symptoms yet differ vastly in treatment and urgency, identifying the likely cause early is critical. A free, instant, online symptom check can help you narrow down possibilities in minutes, understand which category your symptoms may fall into, and guide your next steps—whether that means monitoring at home or seeking prompt medical care.

Reviewed for medical accuracy: 07/14/2026

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Important Next Steps

Learn if mild fever and fatigue are seriousDiscover likely causes of your fever and fatigueFind out what might be causing fatigueSee OTC options for fever and fatigueFind a doctor for fever and fatigueUnderstand home remedies for fever and fatigueCheck symptoms behind mild fever and fatigue

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Explanation

When both mild fever and fatigue are present, it is often caused by a cold or various viral infections. However, if symptoms persist for a long time, chronic infections such as chronic hepatitis or tuberculosis, or the possibility of autoimmune diseases or cancer should also be considered. If you have any concerning symptoms, you can start by using a free AI symptom checker to help identify possible causes before consulting your health care provider.

(References)

  • Balli S, Shumway KR, Sharan S. Physiology, Fever. [Updated 2023 Sep 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

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