Why won't my low fever go away?

September 27, 2025 •

5 min read

According to the Centers for Disease Control and Prevention (CDC), chronic diseases are a leading cause of death and disability in the US, and a low-grade fever can sometimes signal a more persistent health issue. This article explores the various reasons behind the question, 'Why won't my low fever go away?'

Quick Summary

A persistent low-grade fever can indicate the body is fighting off a lingering infection, but it can also be a sign of underlying conditions like autoimmune diseases, side effects from medication, or even chronic stress. The cause determines the appropriate course of action, and medical evaluation may be necessary if the fever persists or is accompanied by other severe symptoms.

Key Points

Lingering Infections: Viral or bacterial infections, even seemingly mild ones like a cold or UTI, can cause a low-grade fever to persist for several days while the body fights them off.
Chronic Illnesses: Ongoing inflammation from autoimmune diseases (like rheumatoid arthritis or lupus) or other chronic conditions (like thyroiditis) is a common cause of persistent low-grade fevers.
Stress-Related Fever: Chronic emotional or psychological stress can trigger a psychogenic fever by affecting the brain's temperature regulation, and it won't respond to typical fever-reducing medication.
Medication Side Effects: Some medications, including certain antibiotics, can cause a persistent low-grade fever as a side effect, a condition known as drug fever.
Monitor and Seek Care: If a low fever lasts more than a few days, is accompanied by severe symptoms like confusion or a stiff neck, or if you are in a high-risk group, it's crucial to seek medical evaluation for a proper diagnosis.
Proper Treatment Requires Diagnosis: Home care can provide comfort, but treating a persistent low-grade fever effectively requires identifying and addressing the specific underlying cause with a doctor's help.

The Lingering Low-Grade Fever

Many of us experience a fever as a temporary symptom of a viral or bacterial infection, like a cold or the flu. It's a natural and helpful bodily response, as an elevated temperature helps the immune system fight off pathogens more effectively. However, when that slight elevation in temperature, typically between 98.7°F and 100.4°F (37.5°C and 38.0°C), persists for more than a few days, it can become a source of worry. A fever lasting more than 10 to 14 days is often considered persistent or chronic. Understanding the potential reasons for this can help you decide your next steps.

Common and Hidden Infections

One of the most frequent culprits behind a low-grade fever that won't go away is a stubborn or hidden infection that your body is still actively battling. Your immune system may be managing the infection well enough to prevent a high fever but not strong enough to eliminate it quickly.

Respiratory Infections: A cold, the flu, or even lingering effects from COVID-19 can cause a low-grade fever that takes longer than expected to resolve. Conditions like bronchitis can also involve prolonged symptoms, including fever.
Urinary Tract Infections (UTIs): These bacterial infections don't always present with classic symptoms like painful urination, especially in adults. A persistent low fever can be a sign of a hidden UTI.
Sinus Infections: Chronic or smoldering sinus infections can cause a low-grade fever for an extended period, especially if they are not treated effectively.
Dental Abscesses: An abscessed tooth is a pocket of pus caused by a bacterial infection. The body's immune response to this localized infection can cause a systemic low-grade fever.
Tuberculosis (TB): Though less common in many developed countries, TB can cause a persistent, low-grade fever, particularly with night sweats, as the bacteria can remain dormant in the body for years.

Chronic Inflammatory and Autoimmune Diseases

Beyond simple infections, a long-term, low-grade fever is often a hallmark of chronic inflammatory or autoimmune conditions. In these cases, the immune system mistakenly attacks healthy cells, causing a low-level, ongoing inflammatory response that elevates body temperature.

Autoimmune Conditions: Diseases like rheumatoid arthritis (RA), lupus, and inflammatory bowel disease (IBD) can cause persistent inflammation that manifests as a low fever. The body's immune system is essentially working overtime.
Chronic Fatigue Syndrome and Fibromyalgia: These conditions are often associated with persistent, mild fever alongside other symptoms like fatigue and muscle pain.
Thyroid Problems: An overactive thyroid (hyperthyroidism), or inflammation of the thyroid gland (thyroiditis), can speed up your body's metabolism and lead to a low-grade fever.

Other Potential Causes

Several other factors, some more benign and others more serious, can contribute to a lingering low-grade fever.

Medications: A low fever can occur 7 to 10 days after starting a new medication, a phenomenon known as drug fever. Certain antibiotics, antihistamines, and blood pressure medications can be the cause.
Chronic Stress: Intense emotional stress can cause a psychogenic fever, which is a real, stress-induced elevation in body temperature. This is because stress can affect the hypothalamus, the brain's temperature control center.
Cancer: Though a fever is a non-specific symptom, a persistent, unexplained low-grade fever can be a sign of certain cancers, such as lymphoma or leukemia. A doctor may run tests to rule this out, but it is important not to immediately assume the worst.
Post-Viral Syndrome: Some people experience a prolonged, low-grade fever as their body recovers from a viral illness. This can be part of a post-viral fatigue syndrome where the immune system remains on high alert.

What to Do: When to Seek Medical Attention

If you're dealing with a low fever that won't go away, monitoring your symptoms is crucial. If the fever lasts for more than a few days, is accompanied by other concerning symptoms, or if you are in a high-risk group (e.g., immunocompromised or elderly), it is time to seek medical advice.

Monitor Duration and Trends: Keep a record of your temperature, noting if it comes and goes or stays constant. A fever persisting for more than 48-72 hours warrants a doctor's call, and anything over a week should be evaluated.
Evaluate Accompanying Symptoms: Look for other signs like night sweats, unexplained weight loss, persistent cough, swelling, stiff neck, or severe headaches.
Check for Drug-Related Fever: If you have recently started a new medication, speak with your doctor to see if it could be the cause.
Prioritize Self-Care: While you wait for an appointment, focus on rest, staying hydrated, and eating a healthy, light diet.

Home Care vs. Medical Treatment

Treatment for a persistent low-grade fever depends on the underlying cause. While home remedies can provide comfort, medical intervention is often needed to address the root issue.


Aspect	Home Care for Low-Grade Fever	Medical Treatment for Persistent Low-Grade Fever
Action	Rest to let your body focus on recovery; Hydration with water, broths, and tea to prevent dehydration; Cooling with light clothing and a cool, damp washcloth; Light Diet with nourishing, easy-to-digest foods.	Diagnosis by a healthcare provider, potentially including blood tests, urinalysis, and other diagnostic tools. Targeted Treatment addressing the specific cause, such as antibiotics for bacterial infections, or anti-inflammatory drugs for autoimmune conditions.
Effectiveness	Provides comfort and supports the immune system's general function. Does not address the underlying cause of a persistent fever.	Can provide a cure or manage symptoms effectively by targeting the root problem.
Safety	Generally safe, focusing on support. Avoid cold baths or ice packs, as they can cause shivering and increase internal temperature.	Must be overseen by a medical professional to ensure correct diagnosis and safe, effective treatment.

Conclusion

In short, a low-grade fever that won't go away is a signal from your body that something is amiss. It can be a harmless lingering effect of a common cold or a more significant indicator of a chronic or hidden health issue. The key is to monitor your symptoms and seek medical advice if the fever persists or other worrying signs appear. A timely diagnosis is the surest way to find peace of mind and get the right treatment. For further medical guidance, you can consult resources like the official CDC website on fevers [https://www.cdc.gov/flu/symptoms/fever.htm].

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Please consult a healthcare professional for diagnosis and treatment.

Frequently Asked Questions

A low-grade fever is a slightly elevated body temperature, typically defined as being between 98.7°F and 100.4°F (37.5°C and 38.0°C).

You should consult a doctor if your low-grade fever persists for more than 48-72 hours, or if it continues for more than 10 to 14 days, as this is often considered persistent or chronic.

Yes, chronic emotional stress can cause a psychogenic fever, which is a real, stress-induced elevation in body temperature that can be persistent. Unlike regular fevers, it doesn't respond to typical fever-reducing medication.

Yes, a low-grade fever can be a side effect of some medications, sometimes called a drug fever, which may appear about 7 to 10 days after starting a new prescription. You should consult your doctor if you suspect this is the case.

Common causes include lingering viral or bacterial infections, underlying autoimmune conditions like lupus, chronic inflammation, or reactions to medication.

You should see a doctor if your fever lasts more than a few days, is accompanied by concerning symptoms like a stiff neck or rash, or if you are at higher risk due to a weakened immune system or chronic illness.

Focus on supportive measures like getting plenty of rest, staying well-hydrated with fluids like water and broth, and wearing light clothing. Avoid strenuous activities that can raise your body temperature.