Cold therapy, also known as cryotherapy, works on the principle of heat exchange. This occurs when you place a cooler object in direct contact with an object of warmer temperature, such as a therapeutic cooling pad against skin. The cooler object will absorb the heat of the warmer object.
Cold therapy is especially helpful in reducing inflammation and controlling pain in acute injuries, but also effective in the treatment of pain and spasm, even in chronic cases. Other problems that respond to cold therapy are bruises, as cold reduces their pain and black marks, headaches, insect bites and muscle spasms.

Therapeutic cooling pads are often used during the first 48 hours of an injury, as in this situation, tissues release a variety of chemicals that produce a cascade effect of reactions, resulting in localized swelling that can cause pain and loss of motion.  Therapeutic cooling pads also known as healing pillows, are one of the most common methods of cold application.
Healling pillows are applied for about 20 minutes at a time. For longer treatment of deeper tissues, it is recommended to get a physician evaluation in order to avoid complications.
Healing pillows are a natural remedy for pain relief, headaches and migraines. After a tissue injury, there is an immediate chemical reaction at the cellular level. Histamines are released in the injured area and cause swelling. Healing pillows reduce muscle and joint soreness, inflammation and swelling in the foot, knee, ankle, hand, wrist, back, and neck, providing relief for arthritis sufferers and carpal tunnel syndrome.
Healing pillows are effective for superficial burns, edema and blistering. For optimal results in cases of trauma, these healing pillows should be applied before significant edema occurs. They also help to stop bleeding, reduce swelling and to ease traumatic pains after an acute injury. Placing healing pillows on the forehead helps to reduce a high temperature.
Cold causes the blood vessels to narrow, that's why it helps to ease headaches and have been proven to help reduce migraine headache pain. Migraine headaches are thought to be due to a dilation of the blood vessels in one half of the head.

These pillows are also helpful in treating some injuries of chronic pain in athletes. For example, an athlete who has chronic knee pain that increases after running can put a cooling pad on the knee to reduce pain and prevent inflammation.
When the ankle is sprained for example, the tissue is stretched and torn and swelling occurs. The sooner we treat the swelling is the better, and the best for this matter is the healing pillows. Cold shrinks the blood vessels which reduces bleeding in the damaged area and helps to prevent swelling. It also helps to prevent the muscles from going into spasm and relieves pain.

The pillows are comfortable to use. They are not like putting ice on the painful or injured place as their cooling is not ice and they are pleasant on the skin.
The use of cold as a treatment is as old thing but today methods of applying cold are more advanced but their principles are the same. Using them should be in intervals. After placing a cooling pad on a sore area for about 15-20 minutes, you should have an interval of at least 30 minutes before replacing it again.