When injecting mannitol, there is pain in the needle or blood vessels, you can give local hot compresses, such as hot towels, warm water bags or salt bags to local hot compresses, you can also give infrared rays to irradiate the location of the pain, which can dilate local blood vessels, promote blood circulation, and help to relieve the pain. You can also give proper massage around the blood vessels, which is also helpful in relieving pain. If long-term treatment with mannitol injections is needed, deep vein puncture can be used to relieve pain, such as the femoral vein, subclavian vein or internal jugular vein, etc. These veins are usually large and relatively easy to reach. These veins are usually larger, thicker, and have a richer blood flow, and are able to quickly transport mannitol throughout the body, thus preventing a large amount from building up in the veins and causing pain.