Final answer:
Ice should be applied for at least 20 minutes to reduce inflammation in the back. It's important to use a towel or ice pack to protect the skin, and apply ice several times a day but not for extended periods to prevent damage.
Step-by-step explanation:
To reduce inflammation in the back, ice should be applied for at least 20 minutes. When using ice for inflammation, it's important to wrap the ice in a towel or use an ice pack to prevent ice burns. Applying ice can help decrease swelling and inflammation and provide pain relief. It is generally recommended to apply ice for short periods of time several times a day, rather than for extended periods, to avoid frostbite or skin damage. Always listen to your body and if you experience excessive discomfort or pain, remove the ice and consult a healthcare professional.