Baby, It’s Cold Outside

By: Alere Staff
Publication Date: Mon, 12/01/2014

Exposure to cold weather over time can cause serious health problems. Whenever temperatures drop below normal and wind speed increases, heat can leave your body more rapidly. According to the dictionary, “wind chill” is the perceived decrease in air temperature felt by the body on exposed skin due to the flow of air. For example, meteorologists will note that, when the air temperature is 40°F, and the wind speed is 35 mph, the effect on the exposed skin is as if the air temperature was 28°F.1

These conditions can affect you and your health. Some situations that can increase a person’s risk for serious health problems include: getting wet, dressing poorly for weather, poor physical condition including exhaustion and predisposing health conditions such as hypertension, hypothyroidism and diabetes.4 If you must go out in the cold, make sure to dress properly, covering all exposed skin and your mouth to protect your lungs.

How the Body Reacts

When exposed to the cold, your body will react in a certain way to protect itself. First, your body will shunt blood to the interior core to protect your vital organs and help maintain your internal temperature.4 Also, the small, lacy blood vessels in and near our skin will contract. While this helps our body from losing more heat and protects the internal organs, it also causes a lack of blood flow to fingers, toes and other outer parts of the body. This reaction lowers the skin temperature, increasing the possibility for frostbite, a medical condition where the fluids in and around the tissue freeze, or hypothermia, a condition where your internal temperature drops.4 Both of these conditions would require you to move to warmer environment or seek medical care immediately.

Warfarin and Cold

When you are taking warfarin and trying to obtain a finger sample during these cold times, remember these basic tips:

  • Be sure you are in a warmer part of your home to help relax those small blood vessels near the skin.4
  • Wash hands in warm, soapy water for 3-4 minutes then rub them together after they are dry to help increase the circulation to your fingertips.2,3
  • You can massage the palm of your hand and even the base of the fingers to increase blood flow.2,3
  • Do not massage your fingertips as this may affect your INR result.2,3



  1. Emergency Preparedness and Response | Safety and Health Guides - Cold Stress Guide.  11/16/2014.
  2. Alere INRatio®2 PT/INR Home Monitoring System User Guide. Collecting a Fingerstick Sample. P 49 – 50. Alere Inc. 07/21/2010.
  3. CoaguChek® XS System User Manual. Tips for a Good Fingerstick. P 15. Roche Diagnostics. 2009.
  4. Out in the Cold - Harvard Health Publications. January 2010.