What organs on the right side can cause pain during a severe flu?

1. How influenza itself can produce abdominal or right‑side pain — an inflammatory ripple effect

Clinical case reports and mechanistic reviews argue that abdominal pain during influenza often reflects a systemic inflammatory response (cytokine dysregulation) from a respiratory infection rather than direct, routine infection of abdominal organs; animal and lab work show influenza can trigger widespread cytokine release and capillary permeability, which may cause intestinal symptoms and distal organ dysfunction in severe cases ^{[5] [4]}. A 2015 review found gastrointestinal symptoms are common in influenza and influenza RNA appears in stools in a substantial minority of cases, suggesting either dissemination or secondary effects that correlate with GI complaints (pooled stool RNA prevalence ~20.6% in that review) ^[1].

2. Which right‑side organs are anatomically plausible pain sources during a severe flu

Medical sources list the main right‑side abdominal organs that can cause pain: upper right — liver, gallbladder, bile ducts, portions of small and large intestine; lower right — appendix; posteriorly — right kidney; reproductive organs (ovary/uterus) may also cause right‑sided pain in people with those organs ^{[2] [3]}. These organs can cause right‑sided pain whether from primary abdominal disease, systemic inflammation, or coincident conditions; clinical evaluation uses location, character, and associated signs to narrow the cause ^[3].

3. Common right‑side abdominal causes that can coincide with or mimic flu symptoms

Viral gastroenteritis (“stomach flu”) and food‑borne illnesses cause abdominal pain, vomiting, and diarrhea but are distinct from influenza; because symptoms overlap, clinicians consider gastroenteritis, appendicitis, urinary tract infection, gallbladder disease, kidney stones, and ovarian pathology when a patient with respiratory flu symptoms develops abdominal pain ^{[6] [7] [8]}. Case reports show influenza can present with an “acute abdomen” picture—tenderness, guarding, and signs prompting surgical evaluation—so clinicians must distinguish primary abdominal emergencies from influenza‑related systemic effects ^[5].

4. Red flags: when right‑sided pain with flu needs urgent evaluation

Authoritative patient guidance notes the flu “very rarely” causes significant tummy trouble in adults, and severe or persistent abdominal pain—or focal right‑lower quadrant pain, high fever, rebound tenderness, persistent vomiting, blood in stool, signs of dehydration or shock—warrants immediate medical attention because conditions like appendicitis, cholecystitis, or complications that mimic an acute abdomen can be life‑threatening ^{[9] [5] [10]}. The Cleveland Clinic and other guides stress that severe abdominal pain localized to the upper right can indicate the liver or gallbladder and should not be ignored ^[3].

5. How clinicians distinguish causes — tests and clues

Clinicians use the pain’s precise location (upper vs lower right), quality (colicky, sharp, dull), timing, and associated symptoms (diarrhea, jaundice, urinary symptoms) plus blood tests, urine/stool studies and imaging (ultrasound, CT) to differentiate influenza‑associated GI symptoms from primary organ disease such as appendicitis, gallbladder inflammation, or kidney problems ^{[3] [8]}. Reviews also mention that in severe influenza, viral RNA found in extrapulmonary sites and immune‑cell carriage can complicate interpretation and may accompany systemic organ effects ^{[4] [1]}.

6. Competing viewpoints and limits of current reporting

Some sources emphasize that most adult influenza cases rarely cause significant abdominal problems and urge caution before attributing abdominal pain to the flu ^[9]. In contrast, virology reviews and case reports document that GI symptoms are common in influenza and that severe cases can involve systemic dissemination or multiorgan injury ^{[1] [4] [5]}. Available sources do not provide a single clear estimate of how often right‑sided organ complications occur specifically from seasonal influenza in adults; estimates and mechanisms vary by study and by virus strain ^[1].

Bottom line: right‑sided pain during a severe flu can arise from influenza‑driven systemic inflammation affecting the gut, from detection of viral RNA outside the respiratory tract, or from a coincident or secondary condition involving the liver, gallbladder, appendix, kidney, or intestines — and severe, focal, or worsening pain requires prompt medical evaluation ^{[5] [1] [3]}.