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What are Common Causes of Fever and Fatigue?

Erin J. Hill
Erin J. Hill

In most cases fever and fatigue are caused by an underlying infection of some sort. Individual conditions which are caused by bacterial or viral infections include influenza, pneumonia, hepatitis, and many sexually transmitted diseases. These are only a few examples of hundreds of potential causes. Occasionally fever and fatigue may be caused by teething in small infants.

As a general rule of thumb, if fever is present in the body, an infection is present somewhere. The type of infection which also causes fatigue and other symptoms is generally a systemic variety rather than one that is localized in one location. The most common type of infections are the common cold and influenza, both of which affect millions of individuals every year around the world.

Inadequate sleep can cause children to become fatigued.
Inadequate sleep can cause children to become fatigued.

Many infections cause fever as well as fatigue because the body’s immune system is working hard to fight off the infection. The temperature begins to rise in an attempt to kill bacteria and viruses, thus causing the fever. Patients often feel tired and fatigued because of this extra energy being exerted by the body, which may encourage them to rest and conserve energy. If vomiting and diarrhea are also present, dehydration may also cause fatigue as well as lowered electrolyte levels.

Bacterial and viral infections commonly cause fever and fatigue.
Bacterial and viral infections commonly cause fever and fatigue.

The only way of getting rid of fatigue and fever caused by a viral infection, the most common type, is to give the body’s immune system time to fight off the virus. There are no medications capable of killing viruses. Bacterial infections may respond to antibiotics, although these are usually reserved for more severe cases.

In some instances, fever and fatigue should be taken seriously and a doctor should be notified. This is the case when a fever becomes very high or doesn’t respond to anti-fever medications like acetaminophen or when fatigue is very severe or long lasting. Some infections can become serious and patients may need help to stay hydrated, relieve symptoms, and maintain proper electrolyte levels until the body heals itself.

Older children are better able to handle fever than younger children.
Older children are better able to handle fever than younger children.

Fever can be serious in young children since their bodies are not able to regulate temperature as efficiently as those of older children and adults. Anti-fever medications are often needed to lower the fever. Additional steps like cold rags or baths and drinking plenty of fluids should also be taken, especially in young infants. If the fever does not subside or gets higher rather than lower, the child’s doctor should be notified. This is especially true if vomiting or diarrhea are present or the child is showing signs of dehydration.

Discussion Comments

honeybees

I have had enough bladder infections in my life to know when one is coming on. Whenever I start feeling a low grade fever and fatigue, I know I better get started on an antibiotic.

Because I am so familiar with the symptoms, I wish I could just call my doctor and tell him what is going on, but I always need to go in and have a urine test.

I have been right every time, and once I get started on the medication, the fever and fatigue go away pretty quickly.

LisaLou

I can tell a difference between feeling tired and total body fatigue. When I am fatigued throughout my whole body even when I have been getting enough sleep, I know I am coming down with something.

Many times this is only a cold or the flu, but this always seems to be my first warning sign. Sometimes if I get enough rest and don't push myself too hard, I can ward it off.

Other times there is nothing I can do, and I know that I am going to be feeling miserable for a few days. Sometimes I have the worst symptoms from a bad cold than from anything else.

Whenever I feel fatigue like this I figure this is my body telling me I need to slow down and take it easy for a while.

Tomislav

I remember hearing stories about fever in babies with the women I work with because it can be such a scary thing for young children.

My husband fought constant tiredness which we thought was due to a fever but as it turns out it went a little deeper than that the fever was due to tonsillitis and his body was just tired from having to fight the infection.

He ended up having his tonsils taken out, which is not a picnic when you are an adult (it actually comes with a 3 to 4 week recovery period where little or no activity can be done). He still is not sure if the surgery was worth not getting sick every year!

I think he will think so after a few more years of fever and fatigue free winters!

orangey03

I got sick often as a child. My mother always said that as long as my fever stayed under 102 degrees, we could just medicate it at home with acetaminophen. If it got above that, we needed a doctor.

I remember spending days at a time on the couch, sweating out my low-grade fever. Acetaminophen really did bring a 100 degree temperature down to 98.6. I just wonder if it prolonged my illness, though, because a fever could have been a good thing, because it meant my body was actively fighting.

I think my fatigue came from dehydration. I always seemed to have a sore throat, and because it hurt so much to swallow, I would refuse to drink more than a sip of liquid.

Oceana

Urinary tract infections usually cause me to develop fever and fatigue. Sometimes, they go away on their own, so I usually wait about going to the doctor until I get a fever or I start vomiting.

I remember one infection that made me feel very ill. I had been fighting it for a couple of weeks. I had to urinate very often, and my bladder cramped. I kept hoping it would go away, but I got fever instead.

My body was tired because I had made it fight the infection alone. I had to go to the doctor for antibiotics, and it took awhile to get better, even with the medication. I lay around feeling fatigued for several days before I began to improve.

wavy58

I try to let my body fight off minor infections by itself, but every time I get strep throat, I go to the doctor to get antibiotics. The swelling is so severe and the fever so high that I simply can’t deal with the symptoms on my own.

The last time I got strep throat, it started out in the morning with a simple sore throat. By that night, I could barely swallow, and my fever was over 100 degrees. I lay in bed feeling like I was burning alive, and I had trouble breathing.

The next day, my doctor gave me a shot of both antibiotics and a steroid. My body was so exhausted from fighting the infection all night that I went home and slept soundly for four hours. I felt much better when I awoke.

OeKc05

I haven’t had the flu in years, because I’ve been adamant about getting a flu shot at the start of the season. I remember how awful it made me feel when I would get it as a child. Fatigue and fever always accompanied my sickness.

It usually started out with vomiting and a sore throat. Then, the diarrhea would come, along with muscle aches. I would develop a fever as the infection progressed, and I would become fatigued and a bit delusional.

I remember one time when I had the flu, my friend came to visit me. I had just woken up from a feverish dream, and I started talking nonsense. I had no idea what was going on, and I felt so exhausted that I just fell back asleep.

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    • Inadequate sleep can cause children to become fatigued.
      By: Susan Stevenson
      Inadequate sleep can cause children to become fatigued.
    • Bacterial and viral infections commonly cause fever and fatigue.
      By: Creativa
      Bacterial and viral infections commonly cause fever and fatigue.
    • Older children are better able to handle fever than younger children.
      By: kmiragaya
      Older children are better able to handle fever than younger children.
    • Most fevers are caused by an underlying infection.
      By: Ocskay Bence
      Most fevers are caused by an underlying infection.
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      By: Alliance
      Many people with fibromyalgia experience chronic lethargy and a low-grade fever.
    • Common symptoms of seasonal influenza include fever, fatigue, and lethargy.
      By: emde71
      Common symptoms of seasonal influenza include fever, fatigue, and lethargy.
    • Fever and fatigue in infants may be cause by teething.
      By: Pavla Zakova
      Fever and fatigue in infants may be cause by teething.