Knee pain causes include:

• ACL injury (tearing of the anterior cruciate ligament in your knee)
• Avascular necrosis (osteonecrosis) (The death of bone tissue due to limited blood flow.)
• Baker cyst
• Broken leg
• Collateral ligament injury
• Dislocation: First aid
• Gout
• Iliotibial band syndrome
• Knee bursitis (inflammation of fluid-filled sacs in the knee joint)
• Lupus
• Medial collateral ligament injury
• Osgood-Schlatter disease
• Osteoarthritis (the most common type of arthritis)
• Osteochondritis dissecans
• Osteomyelitis (an infection in a bone)
• Patellar tendinitis
• Patellofemoral pain syndrome
• Posterior cruciate ligament injury
• Pseudogout
• Referred pain from hip area
• Septic arthritis
• Sprains (Stretching or tearing of a tissue band called a ligament, which connects two bones together in a joint.)
• Tendinitis (A condition that happens when swelling called inflammation affects a tendon.)
• Torn meniscus

Get a ride to urgent care or the emergency room if your knee pain is caused by a major injury. You need urgent medical attention if:

• Your knee joint is bent or deformed.
• There was a "popping" sound at the time of injury.
• Your knee can't bear weight.
• You have intense pain.
• Your knee swelled suddenly.

Make a medical appointment

Make an appointment with your health care team if your knee pain happened after forceful impact or injury. Or if your knee joint is:

• Badly swollen.
• Red.
• Warm and tender.
• Very painful.

Also, call your care team if you have a fever or other symptoms of sickness. You could have an underlying illness. Some minor, ongoing knee pain should be checked as well. If your knee pain bothers your sleep or daily tasks, call a medical professional.

Self-care for knee pain

Start with self-care if your knee pain has no clear signs of trauma and you can still go about daily life. Maybe your knee pain came on slowly over time. Maybe you moved differently, changed routines or had a small injury. In these cases, self-care at home may help relieve your knee pain.

Long-term knee pain is often due to arthritis. Arthritis can happen due to age, past trauma or heavy use. Also, it can happen when the knee joint is unstable or carries too much weight. Low-impact exercise and weight loss may help treat painful arthritis of the knee. Exercise helps strengthen the joint. Weight loss, if needed, lightens pressure. To care for your knee pain at home:

• Rest your knee joint. Stay off your feet as much as possible. Use a cane, walker or other form of mobile support until your knee is healed.
• Switch to low-impact movement. Stay active but try movement that's easy on your knee joints. You might swim instead of jogging, or cycle instead of playing tennis.
• Ice your knee. Wrap a bag of ice cubes or frozen vegetables in a towel. Then, place it on your knee for 15 to 20 minutes. Do this a few times every day.
• Wrap your knee. Wrap an elastic bandage around your knee. Or use a knee brace for support. This is called compression. The wrap should be snug but not too tight. The right compression should control swelling of the knee. But it should not cause pain or swelling in other parts of the leg.
• Prop your knee up. Lie down and place pillows underneath your knee. Your knee should be above your heart. This is called elevation. It may help control pain and swelling.
• Try pain relievers. Many pain relievers you can buy without a prescription. Begin with topical creams or gels. Products with 10% menthol (Icy Hot, BenGay), or diclofenac (Voltaren) may relieve pain without pills. If those don't work, try NSAIDs, also called nonsteroidal anti-inflammatory drugs, or Tylenol, also called acetaminophen. NSAIDs help reduce pain and swelling. They include ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve). But NSAIDs aren't right for everyone. Take Tylenol if you have kidney trouble, high blood pressure, are over 75 or are prone to stomach upset.