Common Signs You're Sick: When to See a Doctor

Illness manifests through a constellation of symptoms that vary by cause. This reference lists the most frequent signs across infectious, inflammatory, and systemic conditions.

General Constitutional Symptoms

• Fever (≥38°C / 100.4°F) or hypothermia (<36°C)
• Chills, rigors
• Fatigue, malaise, exhaustion
• Anorexia, weight loss
• Night sweats

Respiratory

• Cough (dry vs. productive; duration, character)
• Dyspnea, tachypnea
• Pleuritic chest pain
• Hemoptysis
• Wheezing, stridor
• Rhinitis: congestion, rhinorrhea, sneezing, post-nasal drip
• Sore throat, hoarseness, dysphagia

Gastrointestinal

• Nausea, vomiting (character: bilious, bloody, coffee-ground)
• Diarrhea (watery, bloody, mucoid; frequency, volume)
• Abdominal pain (location, radiation, character, triggers)
• Constipation, obstipation
• Hematochezia, melena
• Jaundice, dark urine, pale stools

Neurological

• Headache (thunderclap, positional, pattern change)
• Altered mental status, confusion, lethargy
• Seizure
• Focal weakness, numbness, speech/vision change
• Neck stiffness, photophobia
• Vertigo, ataxia

Dermatologic

• Rash (morphology, distribution, evolution, blanching)
• Petechiae, purpura (non-blanching = vasculitis/meningococcemia/DIC)
• Urticaria, angioedema
• Vesicles, bullae, pustules
• Erythema, desquamation

Musculoskeletal

• Myalgia, arthralgia, arthritis (swelling, warmth, effusion)
• Back pain (mechanical vs. inflammatory vs. referred)
• Muscle weakness

Cardiovascular

• Palpitations, tachycardia, bradycardia
• Chest pain (typical vs. atypical)
• Edema (peripheral, sacral, pulmonary)
• Syncope, presyncope

Urinary

• Dysuria, frequency, urgency, hesitancy
• Hematuria (gross vs. microscopic)
• Flank pain
• Incontinence

Red Flags: Seek Care Immediately

• Difficulty breathing, chest pain, syncope
• Fever >39.5°C (103°F) or >3 days
• Altered mental status, severe headache + neck stiffness
• Non-blanching rash
• Hemoptysis, hematemesis, melena, bright red blood per rectum
• Sudden severe pain (abdomen, head, flank, testicle)
• Focal neurological deficits
• Inability to tolerate oral fluids >24h (dehydration risk)

When to Schedule a Visit

• Symptoms >7–10 days without improvement
• Recurrent or cyclic symptoms
• Symptoms interfering with work/school/sleep
• New symptom in context of chronic disease
• Medication side effects suspected

Symptoms are the body's language. Context (duration, severity, trajectory, risk factors) determines urgency. When in doubt, get evaluated.