Chills and fever usually resolve within a few days with rest, fluids, and over-the-counter fever reducers. The key is working with your body’s process rather than against it: warming up during the chill phase, cooling down once the fever breaks, and staying well hydrated throughout. Most fevers in adults are caused by common infections and don’t require emergency care unless they climb above 103°F (39.4°C) or come with certain red-flag symptoms.
Why Chills and Fever Happen Together
Chills aren’t a separate problem from fever. They’re the opening act. When your immune system detects an infection, it triggers the release of inflammatory chemicals that ultimately produce a signaling molecule called prostaglandin E2. This molecule acts on a small region deep in your brain, the body’s internal thermostat, and resets your target temperature higher than the normal 98.6°F.
Once that new set point is established, your brain treats your current normal temperature as “too cold.” It responds the same way it would if you walked outside in winter: blood vessels near your skin constrict to trap heat, your muscles contract rapidly (shivering), and you feel an intense urge to bundle up. That shivering is your body generating heat to reach its new, higher target. Once your temperature climbs to meet the new set point, the chills stop and you feel hot instead. This is why chills come first and fever follows.
What to Do During the Chill Phase
When you’re shivering and feel cold, your body is actively working to raise its temperature. Fighting that process by stripping off blankets or applying cold compresses can backfire. Clinical guidelines from the UK’s National Institute for Health and Care Excellence recommend that a person with fever should be “neither underdressed nor overdressed,” with clothing adjusted for comfort rather than aggressive cooling. Removing layers from someone who is still shivering can increase metabolic stress, because the body compensates by generating even more heat.
During the chill phase, use a light blanket and comfortable clothing. Once the shivering stops and you start feeling warm or flushed, that’s the signal to remove the extra layer. Keeping heavy blankets on after the chills pass can trap excess heat and push your temperature higher than it needs to go.
Bringing Down the Fever
Over-the-counter fever reducers work by blocking the production of prostaglandin E2, which effectively tells your brain’s thermostat to lower the set point back toward normal. For adults, ibuprofen (400 mg every 6 to 8 hours) or acetaminophen are the two standard options. You can alternate between them if one alone isn’t providing enough relief, but don’t exceed the maximum daily dose listed on the packaging for either.
For children, both acetaminophen and ibuprofen are appropriate, but ibuprofen should not be given to babies younger than 6 months without a doctor’s guidance. Dose by weight, not age, using the chart on the product label.
Never give aspirin to children or teenagers with a fever. Aspirin has been linked to Reye’s syndrome, a rare but serious condition that causes swelling in the liver and brain, particularly in young people fighting viral infections like the flu or chickenpox. Aspirin also hides in combination products like Alka-Seltzer and some herbal remedies, so check labels carefully. It may be listed as acetylsalicylic acid, acetylsalicylate, or salicylate.
Skip the Ice Bath
It’s tempting to try a cold bath or ice pack when a fever spikes, but external cooling works against your body’s reset thermostat. Your brain still “wants” the higher temperature, so cold exposure triggers more shivering, vasoconstriction, and discomfort as your body fights to maintain the fever. Research comparing tepid sponge baths to no sponging found that while sponged patients cooled slightly faster in the first hour, there was no meaningful temperature difference after two hours. The sponge bath group did, however, have significantly higher discomfort scores, including more crying, shivering, and goosebumps.
If you want external cooling, a lukewarm (not cold) washcloth on the forehead can feel soothing without triggering a strong shivering response. Save it for after you’ve taken a fever reducer, when the thermostat set point is already dropping.
Staying Hydrated
Fever increases water loss through your skin. For every degree Celsius above 100.4°F (38°C), your body loses roughly 10% more water through the skin than it normally would. Combined with sweating, faster breathing, and reduced appetite, dehydration can develop quickly, especially in children and older adults.
Water is fine for most adults. For children or anyone with prolonged fever, an oral rehydration solution or drinks with electrolytes help replace lost sodium and potassium. Sip steadily rather than trying to drink large amounts at once, which can cause nausea when you’re already feeling unwell. Pale yellow urine is the simplest sign that you’re keeping up with fluid losses.
Rest and Environment
Your body is spending significant energy fighting infection and generating heat. Rest isn’t optional, it’s part of recovery. Keep the room at a comfortable, moderate temperature. A room that’s too warm traps heat once the fever peaks; a room that’s too cold worsens chills. Around 68 to 72°F (20 to 22°C) works for most people. Light, breathable clothing and bedding let your body regulate more effectively than heavy pajamas or thick comforters.
Fevers That Need Medical Attention
Most fevers resolve on their own within three days. Certain situations call for prompt medical care:
- Infants under 3 months with any fever need immediate medical evaluation, regardless of how well they appear.
- Adults with temperatures of 103°F (39.4°C) or higher who look and act visibly sick should seek care, especially if the fever doesn’t respond to medication.
- Fever lasting more than 3 days in an adult, or more than 24 hours in a child under 2, warrants a call to your doctor.
Certain symptoms alongside a fever point to serious conditions that require emergency care. A stiff neck combined with a severe headache, confusion, and vomiting can signal meningitis, a brain infection that can become fatal within days without antibiotic treatment. A spreading rash that doesn’t fade when you press on it, particularly small red or purple spots, is another red flag. Difficulty breathing, persistent chest pain, seizures, or an inability to keep fluids down also warrant an emergency visit rather than waiting it out at home.