Damage to the structures of the knee commonly causes inflammation and swelling, also called fluid on the knee. The swelling may occur suddenly after a traumatic injury to the knee, or it may be a long-term problem for patients with gout or arthritis. Mild to moderate swelling responds well to the RICE protocol--rest, ice, compression and elevation, according to the Mayo Clinic. If the knee becomes warm and red, cannot bear weight, feels numb or is misshapen, the patient should seek medical attention, according to the National Institutes of Health.
Rest the affected leg. If you injured your knee while exercising, stop the activity immediately. If the swelling is a long-term problem, avoid over-using the knee as much as possible.
Apply an ice pack or package of frozen vegetables to the affected knee for 20 minutes every hour while you are awake to reduce pain, inflammation and swelling, according to the Mayo Clinic. Avoid skin damage by wrapping the ice in a towel and removing it after 20 minutes.
Wrap the knee in an elastic bandage to prevent further swelling and to stabilize the joint. The bandage should be snug but not tight. If your toes begin to tingle or feel numb, remove the bandage and re-wrap it.
Elevate the affected leg on pillows when you are sitting or lying down. Elevation helps the fluids drain away from the knee rather than accumulating there.
Take over-the-counter anti-inflammatory medications such as aspirin, naproxen or ibuprofen to relieve swelling, inflammation and pain, according to the American Academy of Orthopaedic Surgeons. Patients with arthritis of the knee may find glucosamine and chondroitin to be helpful as well.