Your Health: When to use either hot or cold therapy

A common question that I am asked in my urgent care practice is when to apply either hot or cold packs to treat injuries and pain.
Acute injuries are usually manifested by pain, swelling, and tenderness, whereas chronic injuries are usually manifested by lingering pain from an acute injury or from overuse of muscles and ligaments from too much exercise or heavy work.
Our necks, backs, shoulders, and knees are common sources of ongoing pain. Chronic pain may come and go, whereas acute pain from a recent injury is usually constant.
Ice is used to treat an acute injury because it helps to slow blood flow to the injured area, thus helping to reduce swelling and inflammation. Ice can be applied by using ice in a plastic bag, gel packs (from a pharmacy) or even from using a bag of frozen peas. In general, cold therapy can be discontinued when swelling is gone after an injury.
Heat treatment may begin several days after the injury. It works by opening up blood vessels, which helps by increasing blood flow to the injured tissue, thus easing the pain. The word heat is defined as very warm to comfortably hot, but not too hot. Heat can be applied by using a hot water bottle, a heating pad, a gel pack or a hot soak in the tub.
Be very careful using heat if you have diabetes or poor circulation as you may cause burns to the skin.
The use of products to apply to the skin overlying a painful body part such as “Deep Heat” or “Mentholatum” work by causing the skin to feel cool and then warm. These feelings on the skin distract you from feeling the aches and pains deeper in the tissue. This may be helpful for more minor aches and pains.
Both hot and cold compresses should be wrapped in a thin towel so that you neither burn nor freeze the skin.
Be aware that you may burn your skin if you fall asleep on a heating pad. Hot or cold packs should be used for 15 to 20 minutes at a time. For ice treatments, I recommend repeating every half-hour to hour if convenient, and for heat, every two to four hours.
In summary:
– Use a cold pack as soon as possible for immediate injuries such as sprains of the ankle, wrist, knee, back or any other injured joint or body part. Cold treatment can usually be stopped 48 hours after the injury or until swelling is gone.
– Use a hot pack for a painful injury that lasts longer than several days, for recurrent pain from previous injuries, or as a warm up of painful areas prior to exercising.
– Terry Hollenbeck, M.D., is an urgent-care physician at Palo Alto Medical Foundation Santa Cruz in Scotts Valley. Readers can view his previous columns on his website, valleydoctor.wordpress.com, or email him at

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. Information in this column is not intended to replace advice from your own health care professional. For any medical concern, consult your own doctor.