Why do I shiver without having fever?
Chills are muscle contractions that help your body warm itself when its temperature drops too low. It happens often if you have an infection and if that case shivering can come with (or just before) having fever. There are though other conditions that can cause chills but no fever.
The first and most obvious reason for chills without fever is cold. If your body is not hot enough because of the environment, it may shiver to get warmer. If the shaking does not stop, even once your body started warming up, it may be a sign of hypothermia and you are then in need of medical assistance.
Chills are caused by a change of temperature of your body and some can also happen after an important physical performance. This happens even more frequently if you exercise in a very cold or very hot environment, and if you are not hydrated properly.
You can find yourself shivering if feeling an especially strong emotion, positive or negative. This is due to a neurobiological reaction of your body and is not dangerous.
Shivers can be caused by a lack of nutrients that prevents your body for functioning correctly. Malnutrition can happen for different reasons but if you suspect you or someone else is suffering it you should immediately talk to a doctor, as this can be especially dangerous.
If you suffer from diabetes and start shivering you should check that you are not having hypoglycaemia, a sudden drop of your sugar levels. If this happens too often, you should talk to your doctor about your diet and the dosage of your medication. Hypoglycaemia can happen even if you do not have diabetes, in that case try to eat something and rest and consult a GP, either through the NHS or a private GP, if this lasts too long or happens too frequently.
Hypothyroidism (underactive thyroid) can increase sensitivity to cold and so cause chills. It is easily diagnosed and treated so if you have ever suspicion because of frequent unexplained chills, consider doing a blood test to check!
Finally, if you are taking any kind of medication (prescription or not) and you start having chills, talk to your pharmacist as it might result from an incorrect dosage.
You must not confuse shivers and your body shaking for no reason. This is called a tremor and can be triggered by different things.
Some tremors are benign although they can be incapacitating. This the case for essential tremors, a common condition for middle-aged and elderly people, or tremors triggered by strong emotions or anxiety.
Some tremors can be a symptom of most serious conditions such as Parkinson or overactive thyroid. A excessive consumption of alcohol or drugs can also explain the tremors.
Tremors are most of the time located in the hands or arms but can also affect other parts. If you experience tremors chronically or if this affects your daily life, you should visit a GP immediately.