Normally, there is a small amount of fluid within a joint for lubrication. When too much fluid builds up in a joint, it’s called effusion. Injury or inflammation of the joint can cause extra fluid to collect there. When this happens, the joint looks swollen and is often painful. It may be hard to fully bend the joint. This occurs mostly in the knee, elbow, ankle, and hip joints.
The most common cause of fluid buildup is wear and tear on the joint cartilage. Other causes include injury to the cartilage, inflammatory arthritis such as gout or rheumatoid arthritis, and infection of the joint.
If the cause of the fluid is not certain, you may need a needle aspiration. This procedure removes a sample of joint fluid from the knee for testing. Removing excess fluid may also help relieve swelling and pain.
Treatment for joint effusion varies depending on the cause. For arthritis-related effusion, rest, ice or heat, and NSAIDs (nonsteroidal anti-inflammatory drugs) are used. If the joint is infected, your health care provider will prescribe antibiotics. In some cases, oral or injected steroids are used to help with pain and inflammation. If these treatments don’t help, surgery may be advised.
Home care
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Rest. Limit your activities. Stay off the affected joint as much as possible until pain improves.
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Ice. Apply an ice pack over the injured area for 15 to 20 minutes every 3 to 6 hours. Do this for at least the first 24 to 48 hours. You can make an ice pack by filling a plastic bag that seals at the top with ice cubes and then wrapping it with a thin towel. Continue to use ice packs for relief of pain and swelling as needed. As the ice melts, be careful not to get your wrap, splint, or cast wet. After 48 hours, apply heat (warm shower or warm bath) for 15 to 20 minutes several times a day, or alternate ice and heat. Never put ice directly on the skin. Always wrap the ice in a towel or other type of cloth.
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Compression. If possible, wrap the affected joint in an ACE bandage to help reduce swelling.
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Elevation. If possible, elevate the affected joint to reduce pain and swelling. This is especially important during the first 48 hours.
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Pain relievers. You may use over-the-counter pain medicine to control pain, unless another pain medicine was prescribed. If you have chronic liver or kidney disease or have ever had a stomach ulcer or gastrointestinal bleeding, or take a blood thinner, talk with your health care provider before using these medicines.
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Assistive devices. If your knee, hip, or ankle is affected, your provider may advise using crutches or a walker. Don't put weight on the affected joint until your provider says it’s okay. Check with your provider before returning to sports or full work duties.
Follow-up care
Follow up with your health care provider as advised.
If you are overweight, talk to your provider about a weight-loss program. The excess weight puts extra strain on your joints.
When to get medical care
Contact your health care provider right away if:
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Another joint starts to hurt or swell.
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Pain, redness, or swelling of the knee gets worse.
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Swelling goes away and then comes back.
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You have a fever of 100.4°F (38°C) or higher, or as advised by your provider.
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You have shaking chills.
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You can't move the joint.
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Red streaks appear near the joint.
Date Last Reviewed: 03/01/2025
© 2000-2026 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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