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SESK: Stuff Everyone Should Know · sesk.info/trav-dvt-flight-length

Long flights can raise the risk of blood clots. How long is a flight CDC flags as raising risk?

Over 4 hours can raise clot risk.

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  1. Longer than 1 hour
  2. Longer than 12 hours
  3. Longer than 4 hours ✔

Why: CDC says air travel, especially flights over 4 hours, may raise clot risk. Sitting still lets blood pool in your leg veins. Standing and walking helps.

Huh, didn't know that: If traveling by car, CDC says to build in breaks to stretch and walk around.

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References

Answer: Longer than 4 hours. CDC says air travel, especially flights over 4 hours, may raise clot risk. Sitting still lets blood pool in your leg veins. Standing and walking helps.

  1. CDC Travelers' Health: Before You Travel wwwnc.cdc.gov/travel/page/before-travel
    flights longer than 4 hours, may increase your risk for blood clots
    Checked 2026-10-10.

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