We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is Knee Fluid?

By D. Jeffress
Updated Feb 13, 2024
Our promise to you
WiseGeek is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGeek, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Knee fluid is a term that usually refers to the excess buildup of fluid in the knee joint that results from an injury or illness. Body joints contain small amounts of a thick, gel-like substance known as synovial fluid that helps to lubricate and protect joint tissue. In normal amounts, synovial fluid reduces friction between bones and helps to prevent erosion of joint cartilage. When a joint such as the knee is injured, the body tends to produce excessive synovial fluid in an effort to protect it. This often leads to additional problems, however, like swelling and a loss of mobility.

A buildup of knee fluid is often known as water on the knee, and can be caused by a direct injury, an infection, or an underlying disease. Trauma from a fall or a sports injury often results in intense pain, swelling, inflammation, and stiffness. In some cases, swelling and tenderness may be so severe that it is impossible to walk or even bend the knee. Conditions not related to injury, such as osteoarthritis, gout, and tumors, usually present very similar symptoms. A bacterial or viral infection can also lead to inflammation in the knee joint and prompt the body to produce excess knee fluid.

It is important for a person to seek medical help when he or she experiences water on the knee. Without treatment, an injured knee can lead to a permanent loss of mobility as well as chronic, worsening pain. A doctor typically conducts a physical examination, orders blood tests, and takes x-rays to help determine the exact causes of excess knee fluid. If tendons, muscles, or cartilage have been damaged due to an injury, the physician may suggest surgery or simply recommend resting and icing the joint. When a doctor suspects an infection, arthritis, or gout, the patient is usually prescribed specialized oral medications to help relieve pain and other symptoms.

Recurring and long-term knee fluid buildup can usually be prevented by carefully following a physician's orders. An overweight person may be instructed to start dieting and exercising to relieve tension. Athletes and other active people may need to stretch thoroughly before events and wear knee braces to provide extra support and cushioning. Individuals who are susceptible to arthritis and gout, especially older people, may need to take dietary supplements, exercise regularly, and schedule periodic checkups with their physicians to make sure that joint problems do not worsen over time.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
By anon1004510 — On Feb 27, 2021

I am a 72 year old female who had my swollen, painful right knee drained today. My concern was and is that the fluid was yellow and not clear as I always thought it to be. My orthopedic surgeon/soctor drained 30ccs. I saw the yellow fluid and it scared me because last week, I started having a very reduced output of urine which is very uncommon for me. I even mentioned it to my husband and he said I needed to see if it continued and let my PCP know about it. Of course the weekend was upon me so I didn’t call her.

I was in terrible knee pain on Monday so my attention was more directed to calling my orthopedic doctor. I honestly hate to let the weekend go by before calling either my doctor back with questions about my two different situations. I honestly hope you can help me to understand my sense of urgency about what more I can do to speed up the process of finding out if I have an infection in my osteoarthritic knee joint where the swelling has occurred. Do I need to ask or suggest to him that I need him to set up an MRI ASAP and lab work? I really would appreciate your advice and suggestions. Thanks so much.

By anon1004509 — On Feb 27, 2021

I saw my Orthopedic Surgeon today for water on the knee and he drained it. The fluid was yellow and looked like urine. I though water on the knee was supposed to look clear like water! I would like to know if my yellow fluid was or is common or uncommon when it’s drained. About a week ago, I started having a considerable decrease in my urine output which is very unusual for me. I even made the comment to my husband and he said I should mention it to my PCP doctor. By Monday of this week, I noticed that my right knee was considerably swollen and puffy on the upper right side and on the upper left inside. I immediately called him my Orthopedic Doc but couldn’t get in to see him until today, Friday, because of getting surgeries and ofc visits caught up due to Covid. I sincerely hope that you can help me to better understand what I’m experiencing because this painful buildup of fluid again is really concerning me. I am a 72 year old female.

By candyquilt — On Apr 24, 2013

@burcidi-- Are you taking anti-inflammatory medication or a pain reliever? Aspirin and a topical analgesic gave me a lot of relief when I was suffering from the same.

By fBoyle — On Apr 23, 2013

@burcidi-- The swelling will go away when your knee has healed. Keep resting, and elevating it. Avoid bending your knee or doing any activity that might further irritate it.

If the swelling doesn't go away in another few days, you should see your doctor. In rare cases, the fluid might have to be drained.

I had fluid buildup in both of my knees once due to bursitis. The sacs of my knee were inflamed because I was bending my knees too much and it caused fluid on the knee. It took close to two weeks for the swelling and fluid to disappear. I rested that entire time and did not bend my knees at all.

By burcidi — On Apr 23, 2013

I fell on my knee last week and developed knee swelling and fluid buildup soon after. I've been to the doctor, nothing is broken and I've just been told to rest, put ice and elevate my leg.

It's been five days and my knee fluid looks the same as the first day. How long will it take for the fluid to go away? Can I do anything to help?

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.