The thermometer spikes above 98.6 – should you take Tylenol or get to an urgent care? Or should you relax and let the fever do its work? Fevers are widely misunderstood, and not all fevers are bad. Even a slight raise in the body’s temperature makes illness-causing viruses less effective, and an elevated temperature might alert to a more serious condition elsewhere in the body.
Let’s take a look at some of the common causes of fevers and what’s really happening:
Viruses are a common cause of fevers. These tiny organisms require a host to survive and reproduce, and almost all viruses make you sick. Examples are the common cold, pneumonia and bronchitis. Once these foreign bodies enter the bloodstream, they stimulate chemicals called paragens, which instruct the brain to turn up the body’s heat to make it more inhospitable to these potential threats. Heat makes white blood cells effective killers, providing more energy to fight the virus.
Viral infections can have other symptoms, which may come before or after the fever. With pneumonia, you can have coughing; with appendicitis or an intestinal infection you can have pain in the abdomen; with a urinary tract infection, you might also have back pain or pain with urination. The fever is the sign that the body’s immune system has been activated and it’s trying to get rid of the virus.
Bacteria is everywhere, and unlike viruses, only a small portion of bacteria make you sick. The body’s reaction to bacterial infections is the same as for viruses, but it can sometimes be more serious. Often the body can fight bacteria back, or antibiotics may be called for for additional help (antibiotics don’t work for viruses). We also use antifungal drugs and anti-parasite drugs for diseases like malaria, which cause the body to experience a roller coaster of spiking fevers.
Vaccines to prevent a bacterial or viral infection prepare our bodies to come in contact with that infection later. So when you get the vaccine, your body’s immune response is stimulated and the body says, “Whoa, what is this?” It then mounts a fever. When you get a vaccine, you’re not really exposed to an active infection, but it tips your body off that sometime in the future you may come across this. Vaccines for diphtheria, tetanus, whooping cough (DTaP) and pneumonia have been known to cause this reaction and spike a fever.
Conditions like rheumatoid arthritis, joint inflammation, lupus and inflammatory bowel disease are examples of autoimmune conditions. These conditions occur when something triggers an allergic response to normal cells in your body. In these cases, the body begins to attack them causing a reaction against itself. So, for a condition like rheumatoid arthritis, your body’s white blood cells think the joints don’t belong there, and they start to attack the joints. This can cause the body to mount a fever. With inflammatory bowel disease, the white blood cells view the cells in the large intestine as an enemy and they attack them, leading to symptoms like diarrhea and mucus in the stool. Why is unclear, but one of the first lines of defense is steroids, which help calm down that inflammatory response.
A cancer cell is an altered cell that has a slightly different makeup than a healthy cell. Our body’s response to these cells is to raise the temperature to help our white blood cells recognize and eliminate them, causing a fever. Most people don’t realize that cancer cells are killed every day in our body; however, some take hold and begin to grow and the body can’t attack them. That’s where more serious medical therapy such as chemotherapy and radiation come in as a way to try to beat those cells into remission. Occasionally, surgery is required to remove the cancerous tissue altogether.
When to see a doctor for fever?
The answer is usually based on age.
Children: Children often spike a fever with the slightest infections because their immune systems are learning and developing. Children are more likely to have a fever as a first presenting symptom. We consider 101.5° F a true fever in a child. When a child has a fever, we look at how they are acting—are they able to eat and drink, are they urinating normally, do they have a stiff neck (which might signal meningitis), is there any noise in the lungs (pneumonia), are they vomiting, do they seem normal mentally? If they’re otherwise behaving normally, then we’re not as worried about fever (unless it spikes to 104-105° F) and usually find that they’ll do a lot better with some Tylenol or Motrin.
Adults: For adults, it depends on what other symptoms they might have. A fever with a mild sore throat, runny nose and a cough that lasts for a few days is usually not a concern. Fever with a severe headache and a stiff neck is a concern and should be seen by a doctor. A cough with some respiratory difficulty, or feeling slightly short of breath accompanied by a fever requires immediate medical treatment. Any type of urinary or gastrointestinal symptom, especially back pain accompanied by a fever, also requires evaluation. If your fever lasts for 7 days, even if there’s no other symptom present, see a doctor.
People 65+: Some elderly patients won’t even spike a fever if they have a serious bacterial infection. This is because their body’s immune response is so compromised and is not able to fight the foreign body in normal ways. Go to the doctor if you have a fever with the following symptoms: any type of chest pain, shortness of breath, persistent gastrointestinal symptoms or urinary symptoms, severe headache, especially accompanied by stiff neck, spreading rash/discolorations of the skin. In addition, sores or wounds that do not heal, persistent sore throat, any type of persistent lump, persistent diarrhea or the presence of blood in their mucus, stool or urine.
Erik Larsen MD, FACEP, is Assistant Director of EMS & Emergency Preparedness at White Plains Hospital. To find out more about emergency medical services at White Plains Hospital, contact us at 914-681-1155.
In an emergency, always dial 911 first.