Body aches and chills: What's causing them and when to see a doctor

Body aches and chills together almost always point to an active infection — most often the flu, COVID-19, a common cold, or a bacterial illness like strep throat, a urinary tract infection, or early pneumonia. Both symptoms come from the same source: your immune system raising your body's temperature setpoint to fight off whatever it has detected.^1,2

What causes body aches and chills?

When your body senses an infection, the hypothalamus — your brain's thermostat — raises your core temperature setpoint. Your muscles shiver to generate heat, which you feel as chills, and the inflammatory chemicals your immune system releases (cytokines) make your muscles ache.^2,3 That same response can be triggered by viruses, bacteria, certain medications, autoimmune disease, and rarely by cancer or a thyroid problem.³

The most common causes

Influenza (the flu)

The flu is the classic cause of sudden aches and chills. Symptoms usually come on within hours and include fever, body aches, chills, dry cough, sore throat, headache, and fatigue. Most people recover in a few days to two weeks, though some develop complications like pneumonia.¹

COVID-19

COVID-19 overlaps with flu — both can cause aches, chills, fever, cough, and fatigue. A test is the only reliable way to tell them apart, and the answer matters because antiviral options differ.⁵

Common cold

Colds can cause mild aches but usually don't produce chills. If you're shivering and feeling deep muscle pain, the flu, COVID-19, or a bacterial infection is more likely than a typical cold.¹

Bacterial infections

Strep throat, urinary tract infections, sinus infections, skin infections (cellulitis), and pneumonia can all cause aches and chills. Bacterial infections often need antibiotics — they don't resolve on their own the way most viruses do.³

Other less common causes

Hypothyroidism, low blood sugar, side effects from certain medications, malaria (in travelers), Lyme disease, and autoimmune flare-ups can all produce chills with or without aches.^2,3,6

What about chills without a fever?

You can absolutely have chills without registering a fever on a thermometer. The shivering happens because your body is trying to reach a higher setpoint — the temperature climb often follows. Non-infectious causes include being cold, hypothyroidism, low blood sugar, anemia, panic attacks, and reactions to certain medications.^2,6

How to relieve body aches and chills at home

For uncomplicated viral illness, focus on rest, fluids, and symptom management:

• Rest. Sleep is when your immune system does its repair work.
• Fluids. Aim for clear urine. Water, broth, and electrolyte drinks all count.
• Acetaminophen or ibuprofen. Either can lower fever and ease muscle pain. Don't exceed label doses.⁴
• Warm layers, not cold compresses. Bundling up helps your body reach its new setpoint faster and reduces shivering.
• Warm fluids. Tea, broth, and soup are calming and aid hydration.

When should you see a doctor for body aches and chills?

See a clinician — same day at urgent care is fine for most cases — if you have:⁴

• Fever above 103°F (39.4°C) in an adult, or any fever in an infant under three months
• Symptoms lasting more than three days without improvement, or that worsen after initial improvement
• Severe muscle pain, weakness, or pain that prevents you from walking
• A localized hot, red, swollen area on your skin
• Painful urination, flank pain, or pelvic pain (possible UTI or kidney infection)
• A known tick bite or recent travel to areas with malaria or other tropical illness
• Underlying conditions — pregnancy, diabetes, immune suppression, heart or lung disease

Warning signs that need emergency care

Call 911 or go to the ER for:^4,7

• Shaking chills (rigors) with a fever above 103°F — this can signal a bloodstream infection (sepsis)
• Trouble breathing or chest pain
• Confusion or new disorientation
• A stiff neck with fever (possible meningitis)
• Persistent vomiting or inability to keep fluids down
• Severe abdominal pain
• Bluish lips or fingertips

Next steps

If body aches and chills are slowing you down and you're not sure what's causing them, urgent care can usually diagnose the most common culprits (flu, COVID-19, strep, UTI) in a single visit. You can find and book same-day urgent care on Solv in under a minute. If your symptoms include any of the red flags above, head to the ER instead.