Fever at Night: Common Causes and Night Sweats

A fever at night, often referred to as nocturnal fever, is characterized by an elevated body temperature that primarily manifests or worsens during the evening and nighttime hours. While a fever is the body's natural response to fight off i

Medically reviewed by Dr. Roshan Basnet, MBBS, MD (Internal Medicine) on 2026-08-25. See the medical review policy.

Introduction

When to get emergency help

Call an ambulance or go to your nearest emergency department now if you have a sudden severe headache, chest pain, trouble breathing, coughing up blood, black or bloody stools, a stiff neck with fever, a rash that does not fade when pressed, slurred speech, one-sided weakness, confusion, a seizure, fainting, or thoughts of harming yourself.

A fever at night, often referred to as nocturnal fever, is characterized by an elevated body temperature that primarily manifests or worsens during the evening and nighttime hours. While a fever is the body's natural response to fight off infection or illness, a recurring or persistent fever at night, especially when accompanied by drenching night sweats, can sometimes signal an underlying health issue that warrants attention. Night sweats are episodes of excessive perspiration during sleep, often to the extent of soaking bedding and nightclothes, even in a cool environment. This article aims to explore the common and less common causes behind these nocturnal symptoms, discuss associated signs, outline diagnostic approaches, and review available treatment options, emphasizing when it's crucial to seek medical advice.

Common Causes

Infections

One of the most frequent reasons for fever at night is an underlying infection. The body's immune system often becomes more active at night, potentially leading to a more noticeable rise in temperature. Common infections that could cause nocturnal fever include:

• Upper Respiratory Tract Infections (URTIs): Colds, flu, bronchitis, and sinusitis are often associated with fever, which may be more pronounced at night as the body fights the virus or bacteria.
• Urinary Tract Infections (UTIs): UTIs, particularly those affecting the kidneys, can manifest with fever, chills, and night sweats.
• Pneumonia: This lung infection can cause high fever, coughing, and sweating, often worsening at night.
• Tuberculosis (TB): While less common in some regions, TB is classically associated with persistent low-grade fever, night sweats, and unexplained weight loss.
• Mononucleosis: This viral infection, often called "mono," can cause prolonged fever, sore throat, and swollen lymph nodes, with symptoms often worsening at night.

Other Causes

Beyond infections, several other conditions can lead to fever at night and night sweats:

• Hormonal changes: Menopause, perimenopause, and other hormonal fluctuations can cause hot flashes and night sweats that may be mistaken for fever.
• Medications: Certain drugs, such as antidepressants, hormone therapies, and some blood pressure medications, can cause night sweats as a side effect.
• Autoimmune disorders: Conditions like rheumatoid arthritis or lupus can cause periodic fevers and night sweats.
• Cancer: Lymphoma and other cancers often present with persistent night sweats, fever, and unexplained weight loss.

When to Seek Medical Attention

While occasional mild fever at night is often harmless, certain red flags require prompt medical evaluation. Seek medical help if you experience any of the following:

• Fever that is very high (over 103°F or 39.4°C) or lasts more than a few days
• Unexplained weight loss
• Swollen lymph nodes in the neck, armpits, or groin
• Severe headache or stiff neck
• Difficulty breathing or chest pain
• Rash that does not fade when pressed
• Fever that returns after resolving
• Night sweats so severe that you need to change bedding or clothing multiple times

Diagnostic Approaches

To determine the cause of nocturnal fever and night sweats, your healthcare provider will typically start with a detailed medical history and physical exam. They may ask about your symptoms, travel history, medications, and any other health conditions. Depending on the findings, diagnostic tests may include:

• Blood tests (complete blood count, inflammatory markers, infection panels)
• Urine tests
• Chest X-ray or other imaging
• Swabs for specific infections (e.g., COVID-19, flu)
• In some cases, more specialized tests like a tuberculosis skin test or autoimmune antibody panels

Treatment Options

Treatment for fever at night and night sweats depends entirely on the underlying cause. For common infections, rest, hydration, and over-the-counter fever reducers (such as acetaminophen or ibuprofen) may help manage symptoms. However, always consult a healthcare provider before taking any medication, especially if you have other health conditions or are on other medicines. For bacterial infections, antibiotics may be prescribed. For hormonal causes, hormone therapy or lifestyle adjustments may be recommended. For more serious conditions like autoimmune disorders or cancer, specialized treatment plans are necessary.

Practical Next Steps

If you are experiencing fever at night or night sweats, consider these steps:

• Monitor your temperature regularly and keep a symptom diary, noting when fevers occur and any accompanying symptoms.
• Stay hydrated and rest as much as possible.
• Keep your sleeping environment cool and use breathable bedding.
• Contact your healthcare provider if symptoms persist, worsen, or if you notice any red flags.
• Be prepared to provide details about your symptoms, duration, and any recent exposures or travel.

Frequently Asked Questions

This content is for educational purposes only and does not replace professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.

For related medicine and condition background, see Ibuprofen.

This article is for informational purposes only and does not replace professional medical advice. Consult your healthcare provider before making medical decisions.

Educational information only. Always consult a qualified healthcare professional for medical advice.