Knee Swelling

Help relieve knee joint pain, swelling and stiffness in swollen knees.

Select a Topic

  1. What Causes Knee Swelling?
  2. Swollen Knees During Pregnancy
  3. Swollen Knees in Children
  4. Foods to Help Reduce Knee Swelling
  5. How to Prevent and Reduce Knee Swelling

What Causes Knee Swelling?

Knee swelling occurs when excess fluid accumulates in or around your knee joint. The medical term for a swollen knee is a knee effusion or water on the knee. Swollen skin, stiffness and joint pain are common symptoms.

Swelling is one of the most common knee problems that doctors see. Many different things can cause a swollen knee, including trauma, overuse injuries or an underlying disease or condition like arthritis. Knee swelling is something that needs to be evaluated by a doctor, especially if the swelling lasts longer than 48 hours or causes intense pain. Your doctor may need to perform a joint aspiration on the affected knee to obtain a joint fluid sample that can help determine the cause of the swelling.

The most common causes of knee swelling are:

  • Arthritis in the knee joint, especially an inflammatory type of arthritis like rheumatoid arthritis
  • Infection of the knee, a serious medical condition that requires immediate treatment
  • Knee injuries or trauma
  • Torn ligament, especially the anterior cruciate ligament (ACL)
  • Cartilage (meniscus) tear
  • Overuse or strain during exercise
  • Obesity or being overweight
  • Water retention or fluid buildup from infection, blood or joint fluid
  • Poor circulation
  • Autoimmune disease, such as rheumatoid arthritis
  • Tendonitis
  • Hypothyroidism
  • Insect bite

Swollen Knees During Pregnancy

During pregnancy, swelling (edema) is common. Blood flow is increased during pregnancy, and the uterus puts pressure on the vena cava, a major blood vessel that returns blood to the heart from the lungs. Fluid retention from these conditions can cause knee swelling. To avoid swollen knees during pregnancy, rest with elevated feet whenever possible to reduce excess fluid in the knees.

Swelling during pregnancy can also be a sign of a serious condition like pre-eclampsia or hypertension. Your doctor should check out any abnormal swelling that is severe, does not get better with rest, involves multiple areas of the body, or occurs with headaches or abdominal pain.

Swollen Knees in Children

Children can get a swollen knee from a fall or injury, but be aware of other possible causes. If your child’s knee swelling or soreness lasts longer than 48 hours, or includes intense pain or a fever, call your doctor.

If you live in a high-risk area for Lyme disease, especially the northeastern United States, it is important to rule that out. Lyme disease can cause persistent joint inflammation and swelling. Septic arthritis, a painful joint infection, can also cause knee swelling in children and should be evaluated and treated by a doctor.

Foods to Help Reduce Knee Swelling

Some foods are known for their success in reducing inflammation. Plus, following a healthy diet will promote overall health and help avoid causes of knee swelling and joint pain such as obesity.

  • Strawberries, blueberries and raspberries are all rich in vitamin C and help promote collagen, which can help prevent joint wear and tear. Vitamin C is a powerful antioxidant that can reduce arthritis inflammation and swelling. Other foods high in vitamin C include broccoli, red peppers, citrus fruits, cabbage, cauliflower and spinach.
  • Foods rich in vitamin B may help reduce joint inflammation and pain, including lean meat, fish, eggs, soybeans, whole grain cereals and lentils.
  • Foods high in vitamin D can help protect joints, including fortified dairy products and fish
  • Omega-3 fats have been shown to reduce inflammation and pain. Salmon, flax seed and walnuts are all rich in omega-3 fats.

How to Prevent and Reduce Knee Swelling

In addition to a healthy diet, there are some effective self-care methods to prevent or reduce swollen knees. If knee swelling or soreness lasts longer than 48 hours, or includes intense pain or a fever of 100.4 or higher, seek medical attention right away.

  • Avoid putting weight on the sore knee as much as possible until the swelling has gone down.
  • Use a cold compress to help reduce knee pain and swelling. Wrap some ice in a cloth and keep it on your knee for 15 to 20 minutes while your knee is elevated. Repeat every 2-4 hours.
  • For arthritis in the knee, stretching and toning exercises are important to help warm and stretch the muscles, especially after long periods of rest.
  • Exercise regularly. Yoga, water aerobics or swimming are gentle low-impact exercises that don’t require you to bear weight on your knee continuously.
  • If you are overweight, consider losing weight naturally. Excess weight puts extra pressure on joints and muscles, especially in the knees and ankles.
  • Massage, which helps release endorphins and other pain-relieving chemicals and supports healthy circulation
  • Consider remedies such as InflammaGo™ for Pain & Stiffness, a homeopathic medicine for mild to moderately sore joints and stiff joints.


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