The 99.8 Fever – What You Need to Know About Low Grade Fevers

The symptoms of illness are vast and various – from generalized weakness, to coughs and a runny nose. But even with a combination of these symptoms, many of us won’t assume sickness. It’s only when we develop a fever that acknowledging the presence of a viral or bacterial infection becomes undeniable.

But what happens if you develop a fever that isn’t quite as pronounced?

99.8 is a low grade fever.

Many will agree that a low grade fever is a difficult symptom to understand, simply because it doesn’t seem to warrant the same aggressive treatment that a full on fever requires. The usual question is whether to treat a low grade fever as is or to wait for a moderate fever to develop before trying anything.

So what’s the right course of treatment for something that doesn’t seem like such a cause for alarm? Find out everything you need to know about low grade fevers, what they mean, and what you can do about them with this detailed guide.

What is a Low Grade Fever?

There’s a bit of a gray area when it comes to assessing fevers. This comes from the fact that temperature can be taken from different parts of the body. Because of the slight variations in the readings you might collect among these different areas, what might be a fever in some sites might not be a fever in others.

To better explain this concept, I’ve put together a simple table to define the borders between fevers depending on where the temperature reading is taken:

Site Low Grade Fever Moderate Fever High Fever
Adult Child Adult Child Adult Child
Axillary 98.6-99.8 99.5-100.4 100.5-101.3 100.5-103.5 ≥101.2 ≥103.5
Temporal 99-100.4 99-100.4 100.4-101.3 100.5-103 ≥101.2 ≥103
Rectal 99-100.4 100-100.4 101.5-102.2 100.5-103 ≥102.2 ≥103
Oral 98.6-100.4 99.5-100.4 100.5-101.3 100.5-103.5 ≥101.2 ≥103.5
Ear 99-100.4 100-100.4 100.4-101.3 100.5-103 ≥101.2 ≥103.5

Keep in mind that when your child reaches the age of 36 months or three years, you should start using the adult fever readings as your basis for determining the presence of a fever. The values shown in the table for children’s fevers apply only to individuals less than three years of age.

Based on the chart above, a low grade fever is a temperature that’s between normal body temperature and a moderate fever. While it might not be as uncomfortable or as pronounced as a moderate or high fever, a low fever can be indicative of specific conditions and infections, giving you a signal as to what you should do about the subtle rise in body temperature.

What Typically Causes a Low Grade Fever?

To better understand how low grade fevers come about, it’s best to first understand what a fever is in general. Basically, a fever is an increase in body temperature, triggered by some sort of infection, illness, or disease. The rise in temperature helps kill off any foreign bodies in our system because certain types of bacteria and viruses can’t survive in warm environments.

In this light, we can assume that a low grade fever indicates the beginning of our system’s defense against potential threats. But what does it mean if a low grade fever never progresses into a moderate or high fever? More so, what does it mean when a low grade fever remains the same over an extended period of time?

Other Possible Causes of a Low Grade Fever

More often than not, a low grade fever indicates either a bacterial or viral infection. However, if your condition doesn’t resolve with OTCs or antibiotics, it’s possible that there’s something else causing the slight increase in temperature.

The second most likely cause for a persistent low grade fever in adults is a reaction to a medication. Some drugs are formulated to slightly increase a user’s body temperature as a side effect of its primary purpose. A common drug known to induce a fever is penicillin.

Strain and sprain have also been known to cause slight fevers. When a part of your body is overworked or injured, you may feel a slightly increased temperature over the affected area. This is your body’s attempt to repair the injury by encouraging more blood to flow through the involved region. Resolving the sprain or strain with rest, pain management medications, and modalities like hot and cold compress should resolve the fever as well.

While they’re not as common, there are a number of other, more serious causes for a prolonged low grade fever. These include, but are not limited to:

  • Arthritis
  • Vasculitis
  • Cancer
  • Acute hepatitis
  • Heat stroke
  • Immunization rejection
  • Stroke
  • Pulmonary embolism
  • Myocardial infarction

It’s important to keep in mind that a fever could indicate a variety of conditions – some easily resolved, and others more complicated and dangerous. With that, it’s ideal that you consult your trusted physician to get a solid diagnosis.

When Should You Worry About a Low Grade Fever?

Generally, a low grade fever shouldn’t be a cause for alarm especially if it’s not accompanied by any other symptoms. If this is the case for you, then simple steps like getting more rest, staying hydrated, and taking over-the-counter fever reducers should be more than enough to help resolve your situation. That said, you don’t need to wait for a low grade fever to develop into a moderate fever before you take action. In fact, doctors recommend that you act as soon as you detect the heightened temperature to help manage the symptoms earlier on.

However, if you’ve been experiencing a low grade fever for several days without resolve and it comes hand in hand with a variety of other symptoms, then it might be time to seek prompt medical care and consultation.

What symptoms should you keep an eye out for in combination with your low grade fever?

  • Chills
  • Generalized weakness
  • Vomiting
  • Bloody stool
  • Altered consciousness
  • Sore throat
  • Shortness of breath
  • Body pain
  • Diarrhea or constipation
  • Loss of appetite
  • Skin color changes
  • Rashes
  • Seizures

If your low grade fever comes in combination with one or a number of these symptoms, it’s strongly recommended that you seek professional medical advice as soon as possible. This is especially true if your fever doesn’t resolve with the use of OTC medications, and remains consistent over a period of 2-3 days.

Treating a Low Grade Fever

While a low grade fever might not be as uncomfortable as a moderate or high fever, it can cause reduced productivity and energy levels. Adding the fact that it could easily develop into a higher temperature later on, it’s ideal that you respond to a low fever before it gets out of hand. Fortunately, low fevers are fairly easy to treat especially if they’re caused by nothing more than a viral infection. In some cases, you might not even need to take medication as low fevers can be treated with simple changes in your lifestyle and level of activity.

Here are a few simple treatment methods you can use to address a low fever:

  • Avoid engaging in physically demanding activities.
  • Stay hydrated. Pumping your system with fluids during the wake of a fever can prevent a lot of complications associated with both viral and bacterial infections.
  • Take more vitamin C. This micronutrient has been known to help boost our immune system to combat common illnesses.
  • Try an OTC fever reducer. Medications like ibuprofen have been known to work wonders when it comes to reducing a temperature, and also provide the added benefit of pain management.
  • Eat healthy. Supply your body with the vitamins and minerals it needs to stay strong during an infection.
  • Avoid anything too sweet. Sugars can easily induce a sore throat when you have a fever.
  • Avoid exposing yourself to too much cold. Take quick, warm showers and make sure to dry yourself completely immediately after.

In Closing

A low fever might seem like a simple issue, but it does serve an important purpose when it comes to determining your current level of health and wellness. So when you start to detect an increase in your temperature, act fast! If your low grade fever persists despite treatment, then make sure to seek out the advice of a licensed medical professional to get a head start on proper treatment.


  1. 99 fever since 26 may, kindly advice

  2. Colleen W. says

    JBaker- your symptoms and length of time having them are almost identical to mine. I’ve had a COVID test (twice), blood work, urinalysis, CT scan of my kidneys and can’t find the problem. My fever is the same as yours, has been going on since February and usually gets worse at night. My only symptoms are feeling tired and feverish. I also seem to have night sweats. The only two theories I have for the cause that haven’t yet been investigated are 1. I have a kidney stone in my right kidney (it has not yet started passing and my urinalysis was fine). 2. I put a medicine called Elidel on my face for eczema that is an immuno-suppressant. Is it possible that it could cause a fever?

    Please update on this page if you find out what has been causing your fever. I am incredibly frustrated about mine.

  3. I have had an on/off low grade fever for several weeks now. But it needs to be said that this has been a chronic issue over the past few years. Comes and goes. When I am in the fever cycle, as I call it, it fluctuates during the day. Always higher at night. I have Graves disease and take Synthroid (no actual gland left). Is it possible I have another auto immune issues? My husband thinks I should also be tested for Lyme. This is not debilitating, just makes me feel crappy. Any ideas?

  4. It could have something to do with chronic stress. Chronic stress builds up inflammation in the body. When the body is very inflamed the immune system has trouble fighting off infections since it’s also trying to fight off the inflammation. Some of you might want to look into a anti inflammatory diet.

  5. Mary McGee says

    I have had a fever since March 16th. I sweat easily, night sweats, shortness of breath, headaches, congestion. Tested negative for SARS-CoV2 twice and waiting on results of 3rd test. I’m a little anemic and have absolutely zero energy. Blood tests show inflammation and ANA, speckled positive at titer 1:80. Serum creatinine is elevated. I’ve had a round of Azithromycin and Doxycycline each and am now on a round of Sulfamethoxazole/Trimethoprim. No RMSF, TB. Had mono in the past. It’s interesting to find others with this low grade fever and no diagnosis and not COVID. I hope we all get well soon. This is crazy making!

  6. Aminu Abdulkareem says

    I have been having a low grade fever for over two months. And I have under goes several test. And all are negative. What should I do please?

  7. Well I have been having the exact same symptoms- intermittent persistent low grade fevers since March 14. Sounds like I’m going down the path many of you guys here have-I’ve had tons of bloodwork, urine tests, chest X-ray, CT scan (chest, abdomen)…nothing abnormal. THE STRANGEST & most frustrating symptom of all is that I will have no fever for 2 days (maybe 3 occasionally?) and I’ll start thinking, ok it’s finally over. And then I’ll start feeling bad/feverish and sure enough, fever!

    My normal temp is 97.7ish, fevers are 99-100.4/5; I don’t normally get fever – only when really sick.

    I’m glad I found this page bc I’m not alone I can see now. But seriously- we cannot be the only ones. And it seems like many of us started around the same time or have had fevers the same amount of time. I hope the medical community is listening.

  8. Gayathri says

    I have throat dryness in past 2 weeks and mild fever 98.6

  9. Muhammad saeed says

    I have low grade fever 99 to100 from 8 days and legs bone pain . Doctor have tested blood cp _ Esr is 17mm/hr – ( Male Ref-valu is 0-10mm/hr) and also blood wdal test and Urine/ RE—blood RFT/B.S.R./ RA factor/H PYLORi. in normal range.
    Doctor suggested claritic 500mg 5 days dose but low grade fever same condition .Now Doctor suggested cap. SEFSPAN 400mg .ones daily .any body help
    I have already kidney pain on Right side
    (Altrasound is normal )

  10. Lisa, have you been to a rheumatologist? You should be checked for Raynaud’s Syndrome. It’s usually comorbid with another autoimmune disease but sometimes it’s a stand alone issue. The main symptom is fingers and toes turning white and blue/black. I have it and was finally diagnosed. It can cause all sorts of vague to extreme symptoms. It’s worth looking into!

  11. peggy stum says

    i have had a low grade fever 99.8 for about a week. what can i do for it

  12. I’ve been having low-grade to moderate fever with fatigue and myalgia for more than two months now. May have been longer – I only started taking my temps daily back in March when the coronavirus became more prevalent because I work in a hospital. I’ve had consults with a cardiologist, hematologist, and immunologist. I’ve had all sorts of bloodwork, a chest xray, 2D echo, abd/pelvic ultrasounds, plus a mammogram. Next on the list is CT’s of chest, abdomen/pelvis and an MRI of my brain. None of the doctors have any idea what’s wrong with me. Very frustrating.

  13. Sharon Edmondson says

    I have been let running a low-grade fever between 95.3 and 97.6 for a couple weeks is it OK for your temperature to stay at 95?

  14. have you ever gotten a blood test to see if your vitamin deficiency?
    I use to get headaches, tiredness and weakness. This was my issue ,

  15. Wilma Mizanoski says

    Have any of you been tested for Lyme’s disease? Teresa…any updates on your condition?

  16. Harpreet kaur bhullar says

    I am having temperature between 98.6 to 99.3.I have dry cough,body aches,weakness,loose stools,vomitting from one month.I did covid test aslo its negative.Doctor did my blood test nothing came in.I am tired of this sickness from one month.I am at home from last months working from home.I do not know what happen to me.Please give me some solution.

  17. I’ve had low grade fever on and off for over a month now. CBC blood work and urinalysis. No one knows why. And body aches. Getting ready to start antibiotic now to see if that helps. Also, had test for flu and Covid. Both negative

  18. I have had a low grade fever every day for 2 months. Bloodwork is normal. I am fatigued and my wrists and neck feel stiff/weak/tired. But other than that- 0 symptoms. No
    One can figure it out. It’s very very frustrating.

  19. My wife has had a low grade fever for nearly 6 weeks. Started with a sore throat/upper respiratory and quickly progressed to pain on her right chest. Fevers daily for about a week. Then no fever for 2 days. Then pain started in upper back and fever returned. Negative for Covid19. After 3 weeks she started having SOB and pain on left chest. Went to ER. XR and CTA negative for pneumonia and PE. CT did show mild bibasilar atelectisis. Dx was bronchitis. Went back to ER with SOB and was admitted to hospital overnight. They tested for all sorts of viruses and did blood cultures for bacteria and fungus; no growth. Negative as second time for Covid19. Here PCP has given up and referred her to an infectious disease doctor.

  20. Hi have been suffering the low grade fever from last 23 days. Blood report shows Typhoid and Urine infection. Admitted in hospital, after 6 days discharge again fever came 99.1. pls suggest

  21. Karlie Gilbert says

    I’ve been running a fever for about a month. I’ve had some weird things come up that looks like auto immune issues. Make sure you ask your doctors to do the ANA testing.

  22. Teresa Says
    I am experiencing the same exact symptoms of a low-grade fever. Although, not quite as long, It’s only been affecting me for roughly 7-10 days. I normally wouldn’t be so concerned as being only a month away from turning 31, however with this COVID-19 virus taking over the world I feel as I should be taking a few precautions. I have barely left my house since the start of the pandemic, but have heard it could take up to 2ish weeks for symptoms to araise. Also, I’m even more concerned because this low-grade fever is causing me very extreme depression as well as feeling extreme weakness. Every muscle in my body is very stiff, and I am feeling beyond exhausted. Would you happen to have any advice from your own personal experience that what helps take the edge off?

  23. I (44/M) have been having low grade fever (100-101 F) for 2 months now and counting. They did all blood tests. CT scans, PET scans but cannot find anything significant to explain. THis is really horrible, i do not know what to do next? 🙁

  24. I’ve had a low grade fever for a little over a year now, with peripheral neuropathy, headaches, dizziness, severe edema (I’m not overweight), pain in bones, chills, sweating, chest pains, abdominal bruising over my liver, constant diarrhea with blood, strange rashes that appear out of nowhere, pain and aches all over, alot of fatigue, difficulty sleeping, toes and fingers that turn white and black, I’m miserable and suffering and I’m afraid to say something, that my doctor will think I’m crazy.

  25. Teresa have you been checked for mono? There is a specific test just for it, won’t show up in regular blood work

  26. Lilah Larkin says

    My husband has had chronic low grade fever since September 2019, (only at night or early morning between 99.4-100.5, never has fever at any doctor’s appointment), along with night sweats, occasional heart palpations, occasional hand and leg tremors. Doctors cannot find anything. He has been checked by infectious disease, rheumatologist, hematologists and next seeing an endocrinologist. He is at his wits end and doesn’t know what to do. He was taking TREMFYA injections for psoriasis (last injection was 9/3, stopped injections thinking his immune system was compromised but no infection was found), testosterone injections (stopped in November to see if symptoms went away, they have not) Any suggestions for next steps?

  27. Scott Morris says

    Hey Teresa,
    Did you ever get this fever issue resolved?

  28. I have had a low grade fever for months. Doctors have tested for so many things and everything is normal. I’m so severely depressed and weak

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