If you are in a hurry
- When diarrhea in an adult comes with a fever, bacterial gastroenteritis or food poisoning such as Campylobacter is not uncommon. If there is a fever or bloody stool, see a doctor the same day
- Campylobacter is the most common cause of bacterial food poisoning, and raw or undercooked chicken is the main source. “It was fresh, so it is safe” is not true
- Call 119 (Japan’s emergency number) for abnormal consciousness, being unable to stand, or large amounts of bloody stool or vomiting blood. Go to an emergency department even at night if you cannot keep fluids down, or if bloody stool comes with a high fever or severe abdominal pain
Hello. I am Shunichi Gamo, MD, PhD, a board-certified pulmonologist and the director of Sendai Airport North Clinic.
Our fever clinic sees not only people with a cough or sore throat but also quite a few adults who come with “fever and diarrhea.” What I often hear then is this:
“I thought it was a stomach bug and waited, but my fever went up and there was blood in my stool.”
In fact, there is an important clue here.
Let me start with the conclusion: when diarrhea in an adult comes with a “fever,” the cause is often not a virus but bacterial gastroenteritis or food poisoning. The most common is Campylobacter, and raw or undercooked chicken is the main source[1].
From the viewpoint of a pulmonologist, this article explains the possible causes of diarrhea with fever, the signs that mean you should see a doctor quickly, how to take fluids at home and cautions about anti-diarrheal medicines, and what to tell us at your visit. For gastroenteritis that is mainly vomiting and spreads through the family (such as norovirus), please see our norovirus article.
From October 4, 2026, we also run the fever clinic on Sundays and holidays
10:00 to 15:00 (no lunch break). No appointment is needed; you are seen by checking in on the day. We tell you the PCR test result on the same day. On Sundays and holidays we run the fever clinic only; there is no general outpatient clinic and no IV drip service. We are closed on Sunday, October 25, and from November the clinic is open on Sundays and holidays as a rule. Notice about the Sunday and holiday fever clinic
Shunichi Gamo, MD, PhD
Director, Sendai International Airport North Clinic
Born and raised locally, he attended Yuriage Elementary School and Yuriage Junior High School in Natori City. After graduating from Tohoku University School of Medicine, he worked at Sendai Open Hospital and Kesennuma City Hospital, and then at Tohoku University Hospital. In April 2021, in the middle of the COVID-19 pandemic, he opened Sendai International Airport North Clinic. Holding to a fever clinic that never turns patients away, he cared for well over 20,000 patients with fever in the two years before COVID-19 was moved to Class 5 under Japan’s infectious disease law.
Society memberships and board certifications
Certified Member and Board Certified Fellow, Japanese Society of Internal Medicine
Board Certified Pulmonologist, Japanese Respiratory Society
Board Certified Allergist, Japanese Society of Allergology
Board Certified Specialist, Japanese Society of Anti-Aging Medicine
PhD in Medicine (Tohoku University)
[Conclusion] Suspect a bacterial cause when diarrhea comes with fever. See a doctor for bloody stool, abdominal pain, or dehydration
You can decide whether to see a doctor for diarrhea roughly by the following three points.
- [Fever and bloody stool]
A temperature of 38°C or higher, blood or mucus (a jelly-like substance) in the stool, or severe abdominal pain - [Fluids]
Drinking cannot keep up with the diarrhea or vomiting, you are passing less urine, or you feel dizzy when you stand up - [What you ate and the people around you]
A few days ago you ate raw chicken sashimi, seared chicken, undercooked chicken, or other raw food, or people who ate the same food also have diarrhea
If either the first or the second applies, please see a doctor the same day. However, if severe abdominal pain continues, you can hardly keep any fluids down, or your consciousness is abnormal, go to an emergency department even at night, or call 119. The third is important information for narrowing down the cause, so please be sure to tell us at your visit. The detailed lines are summarized in the chapter “Signs that mean you should see a doctor quickly” below.
Common causes of diarrhea with fever: Campylobacter and Salmonella
Viral versus bacterial
The causes of gastroenteritis (an illness in which germs enter the stomach and intestines and cause diarrhea or vomiting) fall broadly into viruses and bacteria. Viral gastroenteritis such as norovirus is characterized by prominent vomiting and easy spread to the family.
Bacterial gastroenteritis, on the other hand, tends to cause fever, abdominal pain, and bloody stool, and is often due to something you ate (food poisoning). The diarrhea guideline of the Infectious Diseases Society of America (IDSA) also calls for testing for bacteria such as Salmonella and Campylobacter in people who have a fever or bloody stool[2]. A fever alone does not prove it is bacterial, but “fever plus diarrhea” is an entry point for suspecting a bacterial cause.
Campylobacter: the most common bacterial food poisoning
Campylobacter is a bacterium that many animals, chickens above all, carry in their intestines. In the food poisoning statistics of the Ministry of Health, Labour and Welfare, of 1,172 food poisoning incidents in 2025, Campylobacter accounted for 220 (1,226 patients)[3]. Among the 315 incidents of food poisoning caused by bacteria, it is the most common cause[3].
According to the Ministry’s Q&A, the incubation period (the time from eating to symptoms) is somewhat long, 1 to 7 days[1]. The main symptoms are diarrhea, abdominal pain, fever, nausea, vomiting, headache, chills, and fatigue, and most people recover in about a week[1]. However, it can become severe in infants, older people, and people with weakened resistance[1].
A review article (a paper that summarizes and explains earlier research) in a US infectious disease journal also gives the typical symptoms as diarrhea, fever, and abdominal pain[4]. Most infections are said to be passed on by eating or preparing chicken[4]. Also, a few weeks after the infection, an illness called Guillain-Barre syndrome, in which the arms and legs lose strength, can occur[1]. It is a rare complication, estimated in the US review at fewer than 1 in 1,000 people[4].
“It was fresh chicken, so it’s fine” is not true
Particularly common sources are raw or half-raw chicken dishes such as chicken sashimi, seared chicken (tataki), chicken wasabi, and chicken liver sashimi[1]. There are Japanese studies that checked how much Campylobacter is present on chicken sold in shops.
In a study of retail meat in Tokyo from 2010 to 2019, Campylobacter jejuni was found in 334 of 626 samples (53.4%) of domestic chicken[5]. In a study of retail chicken in Saitama Prefecture, too, 60 of 168 samples (35.7%) were positive for Campylobacter, and Salmonella was found in 100 of 172 samples (58.1%)[6].
The Ministry of Health, Labour and Welfare also states clearly that, because even healthy chickens carry the bacteria, “it was fresh, so it is safe” is not true[1]. Moreover, infection can occur with as few as a few hundred bacteria[1]. The basics of prevention are to heat the center of chicken to 75°C or higher for at least 1 minute, and not to handle other food with hands, knives, or cutting boards that touched raw meat[1].
Dr. GamoQuite a few people say, “I thought I had cooked it properly.” Whether the center was cooked through is hard for the person eating to tell. If you can think of a meal that might be responsible, please tell us just as it was.
Salmonella and enterohemorrhagic E. coli
Salmonella is also a bacterium that spreads from chicken, eggs, and other foods, and in the Saitama study above it was found in 58.1% of retail chicken[6]. In 2025 there were 25 food poisoning incidents with 662 patients, which means many patients per incident and a tendency to occur in groups[3].
Enterohemorrhagic E. coli (toxin-producing E. coli such as O157) caused 10 incidents and 362 patients in 2025[3]. Although the number of incidents is small, bloody stool can progress to hemolytic uremic syndrome (a complication in which the kidneys and other organs suddenly worsen; also called HUS), so particular care is needed.
[Signs that mean you should see a doctor quickly] Bloody stool, severe abdominal pain, high fever, dehydration, older age
Call 119 right away
If even one of the following applies, call 119 without hesitation, even at night or on a holiday.
- Slow to respond when called, or dazed (abnormal consciousness)
- Limp and unable to stand or walk, or feeling faint when standing
- Large amounts of bloody stool or vomiting blood
- Trouble breathing, or very rapid breathing
Go to an emergency department the same day, even at night or on a holiday
In the following situations, do not wait until morning; go to an emergency department. If the person is in too much distress to be moved, call 119.
- You can hardly keep any fluids down, vomit right after drinking, or have not passed urine for half a day or more
- Bloody stool comes with a high fever or severe abdominal pain
- Severe abdominal pain continues, the abdomen is very painful when pressed, or the abdomen is tight and swollen
- An older person or a person with a chronic illness who cannot keep fluids down and is limp
The IDSA guideline also says that people with diarrhea of any age need to be assessed for dehydration (a state in which the body is short of water), with higher risk especially in small children and older people[2]. If you cannot tell whether it is serious enough to call an ambulance, you can consult the Miyagi Prefecture adult emergency phone consultation line (#7119, which advises adults on whether to call an ambulance or go to a hospital).
See the fever clinic the same day (the next morning if it is night)
Even if breathing, consciousness, and fluid intake are maintained, do not wait too long in the following situations.
- Diarrhea comes with a temperature of 38°C or higher
- Even a small amount of blood or mucus is mixed in the stool
- A few days ago you ate raw chicken sashimi, seared chicken, undercooked chicken, or other raw food, or people who ate the same food also have diarrhea
- Older people, pregnant women, people with chronic conditions such as diabetes or kidney disease, and people taking medicines that suppress the immune system
- The diarrhea continues and you feel that drinking cannot keep up
For an adult with “just diarrhea,” it is often fine to take fluids and watch. But if any of the above applies, think of a bacterial cause and have it checked early. If your condition changes during the night, go back to the “call 119” and “emergency department” guideposts above and judge again from that point.
Please note that we cannot give IV drips in our Sunday and holiday fever clinic. If you can hardly keep any fluids down and are limp, go to a medical institution that can give IV drips.
What you can do at home: how to take fluids, and cautions about anti-diarrheal medicine
For fluids, use oral rehydration solution, a little at a time
With diarrhea, fluids matter most. In the IDSA guideline, the first choice for treating mild to moderate dehydration is oral rehydration solution (a drink that combines water, salt, and sugar in proportions that are easily absorbed)[2]. Severe dehydration needs an IV drip[2].
Drinking a lot at once makes vomiting more likely, so drink one sip at a time, more often. How to give oral rehydration solution, and the guideposts for when drinking is not possible, are explained in detail in our oral rehydration article. It is written for children, but the content applies to adults as it is.
You do not need to force yourself to eat. When you can drink, bring food back little by little, starting with easily digested foods such as rice porridge or udon noodles.
Do not use over-the-counter anti-diarrheal medicine on your own when there is fever or bloody stool
This is actually quite an important point. Over-the-counter anti-diarrheal medicines such as loperamide stop the movement of the intestines. Policies differ by country and by medical institution, but the IDSA guideline says they may be used for “watery diarrhea without fever” in adults with a normal immune system[2].
On the other hand, for diarrhea with fever or inflammatory diarrhea such as bloody stool, they should be avoided at any age[2]. This is because stopping the movement of the intestines can cause toxic megacolon (a serious condition in which the bowel becomes paralyzed and greatly swollen)[2]. The guideline asks that they not be used for any kind of diarrhea in children under 18[2].
There is also a study that raises concern about enterohemorrhagic E. coli (O157). It examined 278 children under 16 who were infected with O157 in a large outbreak in Washington State, USA, in 1993[7]. Of the 278, 37 (14%) developed hemolytic uremic syndrome[7]. In children who took an anti-diarrheal medicine within 3 days of onset, the risk of this complication was 2.9 times higher (odds ratio 2.9, 95% confidence interval 1.2 to 7.5)[7].
An odds ratio is a number that shows “how many times more likely the illness is when a factor is present,” and a 95% confidence interval is “the range in which the true value roughly lies.” Because the lower value is above 1, it means the link between anti-diarrheal medicine and the complication is hard to explain by chance. It is a study in children, but it shows the danger of stopping the movement of the intestines in diarrhea with blood.
Diarrhea is also the body’s reaction to push germs and toxins out. When there is a fever or bloody stool, do not stop it with an anti-diarrheal medicine; take fluids and see a doctor.
What happens when you see a doctor? Stool tests and antibiotics
A stool test looks for the bacteria causing it
At the examination, we ask about the fever, abdominal pain, the state of the stool, what you ate, and illness going around, and we examine the abdomen by touch. Depending on the degree of dehydration, a blood test or an IV drip may be needed.
The test that confirms the causative bacteria is a stool culture (a test that grows the bacteria in the stool to identify the type). The US review also says that stool culture is the most reliable way to diagnose Campylobacter[4]. The IDSA guideline also recommends stool tests for Salmonella, Campylobacter, O157, and others in people with fever, bloody or mucus-containing stool, or severe abdominal pain[2].
A stool culture takes a few days to give a result. So whether to do the test, and whether to start treatment without waiting for the result, is decided by the doctor at the examination.
Antibiotics are given when the doctor judges them necessary. If prescribed, finish them
Whether to use antibiotics (medicines that kill bacteria) for bacterial gastroenteritis is judged by the doctor from the severity of symptoms, chronic conditions, age, and the suspected bacteria. Different medicines work for different bacteria, and bacteria that medicines do not work well against are not rare. In the Tokyo study, 262 of 631 strains (41.5%) of Campylobacter jejuni isolated from retail meat were resistant to a certain antibiotic (ciprofloxacin)[5].
The basic rule is to start without hesitation when needed, and take all that was prescribed to the end even if you feel better. If you stop partway, bacteria may remain or bacteria that medicines work poorly against may increase. Do not take leftover antibiotics from before, or a family member’s medicine, on your own judgment. Choosing a medicine that suits the suspected bacteria is the doctor’s job.
What to tell us when you see a doctor [what you ate, and people who ate the same food]
In diagnosing gastroenteritis and food poisoning, what you tell us is as important as tests. Please bring the following as notes, or enter them in the pre-visit questionnaire.
- Since when the diarrhea, fever, and abdominal pain began, how many times you have had diarrhea, and the state of the stool (watery, mixed with blood, mixed with mucus)
- What you ate up to a week ago (chicken sashimi, seared chicken, yakitori or barbecue chicken, eggs, beef, raw seafood, well water or spring water, and so on). Campylobacter symptoms appear 1 to 7 days after eating[1]
- Whether people who ate the same food have diarrhea or fever (family, coworkers, the people you dined with)
- Whether you have vomited and how many times, the time you last passed urine, and how much fluid you are able to drink
- Medicines you have taken (over-the-counter anti-diarrheals, fever reducers, stomach medicines, and so on) and the time you last took them
- Chronic conditions, the medicines you usually take (medication notebook), and whether you are pregnant
- Overseas travel, contact with pets or animals, and gastroenteritis going around in your area
In particular, “what you ate” and “how the people who ate the same food are doing” are information that only you can give. Please tell us whatever you can remember. When several people who ate the same food are sick, the public health center may also investigate it as food poisoning.
How to see our fever clinic [no appointment, also on Sundays and holidays]
The fever clinic at Sendai Airport North Clinic (Mitazono, Natori City) sees patients not by a reserved time slot but through the pre-visit questionnaire and same-day check-in. Our policy is that we do not turn away anyone who comes to the fever clinic (depending on the symptoms, we may direct you to a more suitable medical institution). People with fever and diarrhea are also seen in the fever clinic.
| Day | Hours |
|---|---|
| Mon, Tue, Wed, Fri, Sat | 9:00 to 12:00 / 14:00 to 18:00 |
| Sundays and holidays (from October 4, 2026) | 10:00 to 15:00 (no lunch break, fever clinic only) |
| Thursday | Closed |
On Sundays and holidays, we are closed on Sunday, October 25, and from November we are open every Sunday and holiday as a rule. On Sundays and holidays we run the fever clinic only, with no general outpatient clinic and no IV drip service. For details, please see Notice about the Sunday and holiday fever clinic.
How a visit works
- Before you come, fill in the pre-visit questionnaire (optional; you may also fill it in when you check in at the entrance)
- Scan the QR code at the fever clinic entrance and check in by choosing “I have arrived, check me in” (required)
- On weekdays, once you have checked in, please wait in your car
- On Sundays and holidays, after check-in we confirm your insurance card (My Number insurance card, certificate of eligibility, and so on) at the general outpatient entrance. The general outpatient clinic is not open on Sundays and holidays, so please feel free to go in. When the confirmation is done, please wait in your car or elsewhere
- When your turn is near, we will call you by SMS or phone. Press the intercom at the fever clinic entrance and give your name
What to bring
- Your My Number insurance card, or a certificate of eligibility or similar
- Your medication notebook (something that shows the medicines you usually take)
- Notes on what you ate, people who ate the same food, and the state of your stool
- Something to drink (oral rehydration solution or water). Keep drinking a little at a time while you wait
Patients are seen in check-in order as a rule, but the order may change depending on the severity of symptoms and other factors. For details, please see About the pre-visit questionnaire and same-day check-in for the fever clinic.
Please note that we cannot give IV drips on Sundays and holidays. If you can hardly keep any fluids down and are limp, please go to a medical institution that can give IV drips.
Frequently asked questions (FAQ)
- I have diarrhea only, with no fever. Should I see a doctor?
-
If you can keep fluids down and have no bloody stool or severe abdominal pain, it is often fine to take oral rehydration solution and watch. See a doctor if a fever develops, blood or mucus appears in the stool, drinking cannot keep up, or you are passing less urine. Older people and people with chronic conditions should come early.
- There is blood in my stool. Should I see a doctor right away?
-
Even if the amount is small, please see a doctor the same day. If bloody stool comes with a high fever or severe abdominal pain, go to an emergency department even at night. For large amounts of bloody stool, or if you are limp and cannot stand, call 119. When there is bloody stool, do not use over-the-counter anti-diarrheal medicine on your own.
- Can I take an over-the-counter anti-diarrheal medicine?
-
The US guideline says it may be used for watery diarrhea without fever in adults with a normal immune system. When there is a fever or bloody stool, however, avoid it, because stopping the movement of the intestines can lead to a serious condition. If you are unsure, do not take it and see a doctor, and if you did take one, tell us the name of the medicine and the time.
- I had diarrhea and fever the day after eating chicken. Is it Campylobacter?
-
The incubation period of Campylobacter is 1 to 7 days, so onset the next day is possible. However, symptoms alone cannot tell it apart from other bacteria or viruses, so we confirm with a stool test when needed. Please tell us at your visit what you ate and how the people who ate the same food are doing.
- I was given antibiotics. May I stop once the diarrhea stops?
-
Please do not stop. The basic rule is to take all that was prescribed to the end, even if you feel better. If you stop partway, bacteria may remain or bacteria that medicines work poorly against may increase. If taking it makes you feel unwell, please talk to us before stopping on your own.
- Can I come to the fever clinic with fever and diarrhea on a Sunday or holiday?
-
Yes. We run the fever clinic on Sundays and holidays from 10:00 to 15:00 (no lunch break). No appointment is needed; you are seen by checking in on the day with the QR code at the fever clinic entrance. We are closed on Sunday, October 25. However, we cannot give IV drips on Sundays and holidays, so if you can hardly keep any fluids down and are limp, please go to a medical institution that can give IV drips.
Summary [Think bacterial for diarrhea with fever, and see a doctor early for bloody stool or dehydration]
- When diarrhea in an adult comes with a fever, bacterial gastroenteritis or food poisoning such as Campylobacter is not uncommon. If there is a fever or bloody stool, see a doctor the same day
- Campylobacter is the most common cause of bacterial food poisoning, and raw or undercooked chicken is the main source. “It was fresh, so it is safe” is not true
- Call 119 for abnormal consciousness, being unable to stand, or large amounts of bloody stool or vomiting blood. Go to an emergency department even at night if you cannot keep fluids down, or if bloody stool comes with a high fever or severe abdominal pain
- For diarrhea with fever, bloody stool even in small amounts, or if you are older, pregnant, or have a chronic condition, come to the fever clinic the same day
- Take oral rehydration solution a little at a time. When there is a fever or bloody stool, do not use over-the-counter anti-diarrheal medicine on your own
- Antibiotics are given when the doctor judges them necessary. If prescribed, take them to the end
- At your visit, tell us what you ate and how the people who ate the same food are doing
If diarrhea you took for a “stomach bug” is joined by a fever or bloody stool, that is an important signal from your body. Please tell us as it is, together with your memory of what you ate. Leave the medical care to us.
That’s all.
Disclaimer
This article is intended to provide general medical information and does not replace an examination, diagnosis, or treatment by a doctor. The content is based on medical knowledge at the time of publication, but the appropriate response differs from person to person. If you are worried about your symptoms, please consult a medical institution.
References
- Ministry of Health, Labour and Welfare. Preventing Campylobacter food poisoning (Q&A) (last revised May 27, 2026). Ministry of Health, Labour and Welfare website. Accessed October 2026. https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/kenkou_iryou/shokuhin/syokuchu/campylobacterqa.html (in Japanese)
- Shane AL, Mody RK, Crump JA, Tarr PI, Steiner TS, Kotloff K, et al. 2017 Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea. Clin Infect Dis. 2017 Nov;65(12):e45-e80. doi:10.1093/cid/cix669 PMID: 29053792
- Ministry of Health, Labour and Welfare. Food poisoning incidents in Reiwa 7 (2025), by causative agent and month. Food poisoning statistics. Ministry of Health, Labour and Welfare website. Accessed October 2026. https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/kenkou_iryou/shokuhin/syokuchu/04.html (in Japanese)
- Allos BM. Campylobacter jejuni Infections: update on emerging issues and trends. Clin Infect Dis. 2001 Apr;32(8):1201-6. doi:10.1086/319760 PMID: 11283810
- Nishino Y, Shimojima Y, Fukui R, Kuroda S, Yamazaki K, Hatakeyama K, et al. [Prevalence and Antimicrobial Resistance of Campylobacter jejuni/coli and Analysis of Macrolide Resistance Isolates from Retail Meat in Tokyo, Japan (2010-2019)]. Shokuhin Eiseigaku Zasshi. 2023;64(5):185-190. doi:10.3358/shokueishi.64.185 PMID: 37880098
- Sakakida N, Sato M, Kando S, Kashima K, Shimada S, Ishii R. [Prevalence of Foodborne Pathogens in Retail Meat in Saitama, Japan]. Shokuhin Eiseigaku Zasshi. 2022;63(4):151-157. doi:10.3358/shokueishi.63.151 PMID: 36047091
- Bell BP, Griffin PM, Lozano P, Christie DL, Kobayashi JM, Tarr PI. Predictors of hemolytic uremic syndrome in children during a large outbreak of Escherichia coli O157:H7 infections. Pediatrics. 1997 Jul;100(1):E12. doi:10.1542/peds.100.1.e12 PMID: 9200386
▶ Summary of this topic: Sunday and holiday fever clinic (from October 4, 2026, 10:00 to 15:00)
Related articles to read when there is a fever
For the Sunday and holiday fever clinic, see Notice about the Sunday and holiday fever clinic; for how to visit, see About the pre-visit questionnaire and same-day check-in for the fever clinic.
