When your body is fighting an infection – either viral or bacterial – it’s common to develop a fever and chills. We know what fevers are, but what are chills?

What are chills?

Since viruses and bacteria have a more difficult time multiplying inside your body at higher temperatures, your immune system (in addition to stimulating a fever) may also make you feel cold, not warm. This is a mechanism designed to make you bundle up and shiver in order to raise your temperature even more, through the rapid contraction of your shivering muscles. When you experience chills it may cause:

• shaking, shivering, or trembling

• chattering teeth

• goosebumps

Chills can even herald a fever. They typically last about a few hours to no more than a day or two. With certain diseases like malaria, dengue, or the flu, chills can be more severe.

What causes chills with a fever?

As noted above, almost anything that can cause a fever can also cause chills.

• Viral infections such (Flu, gastroenteritis, meningitis, and sinusitis )

• Bacterial infections (UTIs, gastroenteritis, pneumonia, meningitis, listeria, strep throat, and sinusitis)

• Parasitic infections (i.e. malaria)

• Sepsis

• Cancers

Related symptoms

Since the fever and chills are themselves symptoms of the underlying illness, any other symptoms you may have will depend. They can include:

• Headache

• Muscle aches

• Fatigue

• Sore throat

• Ear pain

• Runny or congested nose

• Cough

• Loss of appetite

• Nausea/vomiting

• Diarrhea

• Abdominal pain

• Rash or hives (usually in children)

How to treat fever with chills?

Since fever and chills usually taper off on their own after a few days, you should stick to the standard home care at first. This includes:

1. Good rest. If you are tired and drowsy, trust your body! Your immune system works best when you have enough sleep and rest.

2. Over-the-counter (OTC) fever-reducing medicines: Even if the fever and chills themselves are helping your body fight the infection, you should take medicine if you are in pain.

3. Acetaminophen or Paracetamol (Tylenol or another store brand)

4. Ibuprofen (Advil or another store brand)

5. Aspirin (Bayer or another store brand)

6. External temperature control: In general, it’s best to trust your body’s instincts if you feel hot or cold. If that means turning up the heat and bundling up even though you are already spiking a fever, that’s fine.

7. Hydrating: Fever and chills will dehydrate you faster than normal. Remember to drink lots of fluids but avoid alcohol or caffeinated beverages (since caffeine can also dehydrate you a bit faster than normal).

Fever and chills — when to see a doctor

If your fever and chills last for more than 3 or 4 days in a row, seek medical help.

Some symptoms that can indicate a more worrisome diagnosis than the common cold are:

• Shortness of breath

• Confusion or irritability

• Frequent or painful urination

• Severe abdominal pain

• Severe headache

• A persistent cough

• Hallucinations

• Sluggishness or severe fatigue

• Stiff neck

• Fever-induced seizures in children

Summary

Fever and chills commonly go together with even mild infections. They are signs of a robust immune system working to fight the infection off.

Stick to supportive care – that is, treatment that help your own defenses operate against the infection. Rest, hydration, OTC medications, and time will be enough in most cases.

However, if you experience the more unusual and severe symptoms listed above, or if your fever lasts more than 3 or 4 days in a row, please seek medical help.

Worried about your child's fever? Read more about fevers in children and what to do here.