Medicines that increase the risk of accidental hypothermia include those used to treat anxiety, depression, or nausea, and some over-the-counter cold remedies. Ask your healthcare provider how your medicines affect body heat.

Shivering increases muscle cell activity, which in turn produces heat. Severe shivering is one of the signs of hypothermia. However, shivering can stop once the body temperature gets even lower.

Other symptoms include shallow breathing; weak pulse; low blood pressure; a change in behavior during cold weather or a change in the way a person looks; excess shivering or no shivering; stiffness in the arms or legs; chilly rooms or other signs that the person has been in a cold place; poor control over body movements or slow reactions.

You should use a thermometer. If the person's temperature appears to be below 95°F (35°C), or you can't read it on an oral thermometer, take the person's temperature again using a rectal thermometer for a more exact reading. This should not be done outdoors. If the thermometer still does not show the temperature or is below 95°F, call 911. The only way to tell accurately if a person has hypothermia is to use a special thermometer that can read temperatures below 94°F (34.4°C). Most hospitals have these thermometers.

You can also use your own body heat to keep the person warm. Keep the person lying down. Lie close to the victim, but be gentle. Don't handle the person roughly. Rubbing the person's arms and legs, as many rescuers are tempted to do, can make the problem worse. It may cause cool blood that had pooled in the extremities to return to the circulation and cause a further drop in core temperature. That is why you should try rewarming a person's trunk before rewarming their extremities.

Older people are at risk of hypothermia not only in cold weather, but in mildly cool temperatures as well. Older people may be vulnerable to hypothermia even when they live in nursing homes or group facilities. These institutions have to be careful when lowering temperatures. That's because older people who are already sick may have extra difficulty keeping warm.

Illnesses that may blunt the response to cold include slow thyroid (hypothyroidism) or other disorders of the body's hormone system; stroke or other disorders that cause paralysis and reduce awareness; severe arthritis, diabetes, Parkinson's disease, or other illnesses that limit activity; any condition that curbs the normal flow of blood; memory disorders.

Wind chill refers to the fact that brisk winds cause more rapid heat loss than calmer weather. Remember to listen to the weather report before going out in cold weather. Weather forecasters often suggest, even when the temperature itself is not very low, that the wind chill factor is low enough for people to stay indoors. Always dress for the weather and take extra layers if you have any doubts about the temperature or weather conditions.