How long should a instant cold pack stay cold? I have a long term injury to my arm, usually I just use ice but I need something I can use when I'm out and about. I bought a pack off of ebay but they only last between 6 and 10 minutes. Look at one of the refreezable packs in a drug store or sports store. We keep something called frozen peas in a cooler for our soccer matches, and it stays cold for at least two hours.