What Are the Signs of Salmonella Bloodstream Infection?

Most cases of Salmonella cause temporary gastroenteritis (food poisoning) with diarrhea and cramping that resolve on their own. However, if the bacteria break through the intestinal lining and enter your bloodstream, the infection can become a life-threatening medical emergency known as bacteremia or invasive non-typhoidal Salmonella (iNTS) ^[1]. The primary warning signs that the infection has spread to your blood include a high, spiking fever that returns after your stomach symptoms have started to improve ^[2], severe and uncontrollable shaking chills ^[2], profound lethargy or sudden confusion ^[3], and new, localized pain in areas outside of your digestive system, such as your joints, back, or chest ^[4].

Why Bloodstream Spread Happens

In typical cases of Salmonella, the infection is contained within the gut. But in some individuals, the bacteria cross the intestinal barrier and circulate throughout the body ^[1]. Once in the blood, the bacteria have a tendency to travel to and infect vulnerable areas of the body, a process called metastatic infection ^[5]. Surprisingly, in a portion of cases, this bloodstream invasion can happen without the patient ever experiencing the classic diarrhea or stomach cramps first ^[6][7].

Red Flag Symptoms of Bacteremia

If you have recently had Salmonella—or have eaten food linked to a recent outbreak—watch closely for these warning signs. They indicate a medical emergency that requires evaluation in an Emergency Department. Urgent care clinics and telehealth services are generally not equipped to manage suspected sepsis or to order the necessary advanced imaging and blood cultures.

• A “Biphasic” or Returning Fever: It is normal to have a fever for the first few days of food poisoning. However, if your fever drops but then returns as a high, spiking fever, it is a strong signal that the infection has reached your bloodstream ^[2].
• Severe, Uncontrollable Chills: Experiencing intense shaking chills (rigors) is a classic indicator that bacteria are actively circulating in your blood ^[2].
• Extreme Lethargy or Confusion: Profound exhaustion, unresponsiveness, or altered mental status (confusion) are symptoms of systemic infection or sepsis, which is a dangerous whole-body response to the bacteria ^[3][7].
• New, Localized Pain Outside the Gut: Because Salmonella can “seed” in other tissues, be alert for sudden pain in your joints (septic arthritis), chest, bones, or back ^[4][8]. The bacteria frequently target the cardiovascular system and can cause serious complications like infected aneurysms or heart valve infections ^[5][9].

Communication Tip: When arriving at the hospital, you can help the triage nurse by stating clearly: “I recently had a Salmonella infection [or ate recalled food] and I am experiencing red flag symptoms of a bloodstream infection.”

Who is at the Highest Risk?

Anyone can develop iNTS, but certain factors increase gut permeability or weaken the immune system, making bloodstream spread far more likely. You should be especially vigilant if you fall into one of these high-risk categories:

• Age: Adults over age 65 and children under age 5 face significantly higher risks of invasive disease ^[10][11].
• Cardiovascular Disease and Medical Implants: People with underlying heart or blood vessel disease—particularly older adults (like men over 50) with a history of atherosclerosis (plaque in the arteries)—are at a uniquely high risk for the bacteria seeding in their blood vessels ^[10][9]. Those with medical implants (like pacemakers, joint replacements, or venous catheters) are also at higher risk because the bacteria easily adhere to these foreign materials ^[10][9].
• Immunocompromised Status: People living with HIV, undergoing cancer treatment, or taking immune-suppressing medications have a decreased ability to fight off the bacteria ^[12][13].
• Blood and Metabolic Disorders: Individuals with sickle cell disease or a history of malaria are uniquely susceptible ^[1][14]. Patients with diabetes or kidney disease are also at elevated risk ^[10][15].

What to Expect if Spread is Suspected

If your medical team suspects Salmonella bacteremia, they will likely order blood cultures to confirm the presence of the bacteria in your blood. Because of the risk of metastatic infection, doctors often rely on specialized imaging, such as an echocardiogram (an ultrasound of the heart) or PET/CT scans, to verify that the bacteria have not settled in your heart, blood vessels, or joints ^[16][17].

Unlike simple food poisoning, a confirmed bloodstream infection often requires a hospital admission. You should prepare for the possibility of an overnight stay. Treatment frequently involves a prolonged course of intravenous (IV) antibiotics ^[18], and in severe cases where the bacteria have infected tissue or medical hardware, surgical intervention to remove the infected tissue may be necessary.