This is probably the most common cause of a fever. When your body is trying to fight off bacteria or a virus, it releases a substance called pyrogen, which, in turn, resets your internal thermostat. In order to create a hostile environment for the intruder, your body raises the temperature. That, of course, makes life a little difficult for you, too. It is just a temporary state, by the end of which you will emerge victorious and overcome the infection.
However, you should see a doctor in cases of persistent fever that doesn’t respond to over-the-counter medications and home remedies, or when the fever is accompanied by severe headaches, difficulty breathing, blood in your urine or stool, redness of the skin, a rash, or vomiting.
The way vaccines work is by stimulating the body’s immune response. Certain molecules of pathogens like viruses or bacteria (not an active infection, though) are introduced into the body to trigger the immune system – so it is able to recognize and fight them in the future. As explained earlier, one of the ways in which our body wards off unwanted intruders is a mounting fever.
This is usually no cause for worry. Post-vaccination symptoms tend to be mild and pass after 2-3 days.
3. Heat Exhaustion
This may happen on hot, humid days when you are overexerting yourself. By definition, heat exhaustion occurs when the body's core temperature rises above 98.6°F (37°C) but not beyond 104°F (40°C).
Under normal circumstances, the body has functions that are meant to cool it down, but when those systems are overcome and fail to do their job, the temperature continues to rise. Other symptoms include dizziness, excessive sweating, weak and rapid pulse, nausea, headache, and cool moist skin with goosebumps when in the heat.
If you suspect you or someone around you may be suffering from this condition, move to a cooler space, preferably air-conditioned. You can bring down the body temperature by placing a wet towel over the skin and drink cold water or a sports drink if you can hold down your fluids. If those measures fail to provide relief within 15 minutes, seek emergency medical care.
4. Alcohol Withdrawal
Alcohol suppresses the central nervous system. In the first few days of withdrawal, the CNS needs to readjust and that may cause a fever. Another symptom of alcohol withdrawal is muscle contractions. If you experience tremors, it may increase your body temperature.
In case the temperature goes above 103°F (40°C) and does not come down within an hour of home treatment, or persists for over 24 hours during withdrawal - you should seek emergency medical care.
5. Blood Clots
It is very important to know that fever can be a symptom of a blood clot!
A blood clot is a clump of blood, which has solidified from a liquid to a gel-like or semi-solid substance. Clotting can be necessary when you get injured or cut, as it prevents you from losing too much blood. However, when it forms in one of your veins, it can travel to your heart and lungs, get stuck and prevent blood flow. This is a medical emergency.
According to experts, fever along with pain, swelling and redness in your leg or shortness of breath could point to a blood clot.
When traveling you are exposed to new types of bacteria different than the ones your body is already accustomed and immune to. The risk increases for travelers to tropical or developing countries. Doctors identify various types of travel-associated infections that cause fever - the most dangerous of these include malaria, dengue, typhoid fever, and chikungunya. All of them begin with flu-like symptoms.
It is important to consult your physician about guidelines for safe food and water consumption overseas. If you experience fevers upon your return from a trip, its best to go get checked.
7. Hormone Disorder Changes
Thyroid hormones T3 and T4 are produced by the thyroid gland, which takes iodine (found in many foods) and converts it to said hormones. Your metabolism is regulated through the release of T3 and T4, but when too much of them is produced, the body goes into a state of hyperthyroidism.
When not treated, it can deteriorate to a thyroid storm. The symptoms are soaring heart-rate and blood pressure as well as a high fever. Besides untreated hyperthyroidism, a thyroid storm can occur because of trauma, heart attack or delivery of a baby. It is a life-threatening condition that should be treated by medical staff immediately!
8. Inflammatory Conditions
Inflammation is the process that occurs in your body when it is fighting against harmful infections, injuries, and toxins. Similarly to the case of infection-induced fever, inflammation triggers the immune system to raise body temperature and create the symptom of fever.
Chronic inflammation is when the response lingers, thus leaving your body in a constant state of alert. This can have various negative effects over time, as the immune system eventually starts attacking healthy tissues in the body. Over time, chronic inflammation can result in tissue death, scarring, and DNA damage, all of which contribute to the development of degenerative diseases, such as cancer.