Spiral SearchThe Difference Between: 18 Look-Alike Conditions and When to Get Help
Side-by-side comparisons of common conditions that look alike, what you can observe, and when to call 911 or get assessed.
Many illnesses and injuries look alike, and symptoms alone cannot reliably tell them apart. Use these comparisons as clues, not a diagnosis. Cards with a red edge include signs that can need emergency care. When in doubt, call 911 or get medical help rather than waiting.
Jump to a comparison
- Common cold vs. flu
- Cold vs. seasonal allergies
- Flu vs. COVID-19
- Tension headache vs. migraine
- An ordinary headache vs. possible meningitis
- Heartburn vs. possible heart attack
- Lightheadedness vs. vertigo
- Dizziness vs. possible stroke
- Dehydration vs. low blood sugar
- Heat exhaustion vs. heatstroke
- Sprain vs. muscle strain
- Sprain vs. broken bone
- Hives alone vs. severe allergic reaction
- Bladder infection vs. kidney infection
- A “pulled calf” vs. a possible blood clot
- Stomach bug vs. appendicitis
- An uncomplicated cough vs. possible pneumonia
- A stable mole vs. a suspicious skin change
The comparisons
1Common cold vs. flu
What you can observe
A cold often develops gradually, mainly affecting your nose and throat. Flu often starts abruptly, with stronger body aches and exhaustion. Symptoms overlap, so this distinction is only a clue.
When to get help
Seek prompt advice if you are at higher risk of complications or feel seriously unwell.
2Cold vs. seasonal allergies
What you can observe
Repeated sneezing and itchy eyes, nose or throat, particularly around pollen exposure, suggest allergies. Allergies may continue for weeks; a cold usually clears within one to two weeks.
When to get help
Persistent or troublesome symptoms deserve assessment rather than repeated guessing.
3Flu vs. COVID-19
What you can observe
Both can cause cough, fever, fatigue and aches. Symptoms alone cannot reliably distinguish them.
When to get help
Testing can help identify the cause. People at higher risk should seek advice promptly because treatment may be time-sensitive.
4Tension headache vs. migraine
What you can observe
A tension headache often feels like pressure or a tight band on both sides. Migraine commonly involves throbbing pain, nausea, and sensitivity to light or sound; movement may worsen it.
When to get help
Arrange assessment for frequent, severe or changing headaches. A sudden, extremely painful headache needs emergency care.
5An ordinary headache vs. possible meningitis
What you can observe
A headache accompanied by fever, stiff neck, confusion, unusual sleepiness or difficulty tolerating light is more concerning. A rash may occur, but is not always present.
When to get help
Get emergency help if meningitis is suspected. Do not wait for a rash or every symptom to appear.
6Heartburn vs. possible heart attack
What you can observe
Heartburn often follows eating and may include a sour taste or regurgitation. A heart attack may cause pressure, squeezing, sweating, breathlessness or pain spreading to the arm, neck or jaw—but can also feel like indigestion.
When to get help
Call 911 for suspected heart attack. A burning sensation does not establish that chest discomfort is harmless.
7Lightheadedness vs. vertigo
What you can observe
Lightheadedness feels like you might faint. Vertigo feels as though you or the surroundings are spinning. Thirst, dry mouth and reduced urination alongside lightheadedness may suggest dehydration.
When to get help
Recurrent or persistent dizziness needs assessment. The description helps a clinician investigate; it does not identify the cause by itself.
8Dizziness vs. possible stroke
What you can observe
Sudden dizziness or loss of balance becomes especially concerning with facial drooping, one-sided weakness, speech difficulty or vision changes.
When to get help
Call 911 immediately, even if symptoms disappear. Use FAST: Face, Arms, Speech, Time to call.
9Dehydration vs. low blood sugar
What you can observe
Dehydration commonly causes thirst, dry mouth, dark urine and less urination. Low blood sugar can cause shaking, sweating, hunger, palpitations or confusion—especially in people taking insulin or certain diabetes medicines.
When to get help
If you have diabetes, check glucose when possible and follow your treatment plan. Seizure or unconsciousness requires emergency help.
10Heat exhaustion vs. heatstroke
What you can observe
Heat exhaustion often causes heavy sweating, thirst, nausea and weakness. Confusion, poor coordination, seizure or collapse during heat exposure suggests heatstroke. A person with heatstroke may still sweat.
When to get help
Call 911 for suspected heatstroke and begin cooling immediately. Do not wait for sweating to stop.
11Sprain vs. muscle strain
What you can observe
A sprain injures the ligaments supporting a joint, often after a twist. A strain injures a muscle or tendon, often after overstretching or exertion. Both can cause pain, swelling and reduced movement.
When to get help
Seek assessment for severe pain, worsening swelling, inability to use the area normally or failure to improve.
12Sprain vs. broken bone
What you can observe
Both may cause swelling, bruising and difficulty bearing weight. A visibly bent limb, unusual angle or exposed bone strongly suggests a fracture. Appearance alone may not distinguish them; an X-ray may be needed.
When to get help
Get urgent assessment if a fracture is possible. Deformity, numbness or a cold/discolored limb requires emergency evaluation.
13Hives alone vs. severe allergic reaction
What you can observe
Hives are raised, itchy patches. Hives with throat or tongue swelling, wheezing, difficulty swallowing, faintness or collapse may indicate anaphylaxis. A severe reaction can occur without hives.
When to get help
Use an available prescribed epinephrine auto-injector as directed and call 911.
14Bladder infection vs. kidney infection
What you can observe
Burning urination and frequent urges can occur with a bladder infection. Fever, chills, pain in the side or back, nausea or vomiting raise concern for a kidney infection.
When to get help
Seek prompt medical advice for urinary symptoms; fever or side/back pain warrants urgent assessment.
15A “pulled calf” vs. a possible blood clot
What you can observe
Pain after exercise may seem muscular, but a clot can also feel like cramping. One leg becoming swollen, warm, tender or discolored is concerning and cannot safely be distinguished at home.
When to get help
Seek urgent assessment for suspected clot. Sudden breathlessness, chest pain or coughing blood requires emergency help.
16Stomach bug vs. appendicitis
What you can observe
A stomach bug commonly causes vomiting and diarrhea. Appendicitis often starts with pain near the belly button that moves to the lower right and worsens. However, appendicitis can also cause diarrhea or pain elsewhere.
When to get help
Get urgent assessment for worsening or persistent abdominal pain, particularly pain moving to the lower right. Do not rely on a home “press test.”
17An uncomplicated cough vs. possible pneumonia
What you can observe
A cough alone does not identify pneumonia. Cough plus breathlessness, fever, chest pain or marked exhaustion raises concern; older adults may become confused.
When to get help
Seek prompt assessment for breathlessness or chest pain. Severe breathing difficulty or sudden confusion requires emergency help.
18A stable mole vs. a suspicious skin change
What you can observe
An ordinary mole is often fairly symmetrical, evenly colored and stable. A new or changing spot, uneven edges, multiple colors, bleeding or crusting deserves attention. A suspicious spot can be smaller than a pencil eraser.
When to get help
Book a medical assessment for a changing or unusual spot. A photograph with a date can help document change.
Also see: heart attack, stroke and cardiac arrest · burns, heatstroke and hypothermia · describing a condition to a dispatcher.