What Causes Sudden Knee Pain Without Injury?

Sudden pain is always concerning, and with all the parts that comprise the knee joint and the increased mobility it allows you, the knee is one of the locations in the body more susceptible to sudden pain. While there are specific causes of knee pain that result from an injury to the knee joint and one of its many parts, it can be more confusing to understand what is causing your knee pain when there has not been an injury.

In these cases, the most common culprit of your sudden knee pain is inflammation, either due to excessive use or flare-ups from another condition. In many cases, this pain can be treated by resting the knee and using other home remedies, but a doctor is the only true way to rule out more severe causes.

Table of Contents

Why Have My Knees Suddenly Started Hurting?

The knee joint is very complex and consists of multiple moving parts. While this is beneficial for general mobility, it also means the knee joint is more prone to injury. Adding in the body weight placed on the knee, there can be quite a bit of stress that can also lead to knee pain, sometimes suddenly and with no perceivable cause.

The extent of knee pain can vary considerably. With all the parts of the knee, certain parts can become stretched out, worn, partially torn, aggravated, or fully ruptured. Some instances can cause intense pain, while others cause pain that only appears when doing certain activities.

What Can Cause Sudden Knee Pain Without Injury?

Many conditions can cause knee pain that is not set off by a type of injury. Some of these conditions include:


Tendons are what connect the joints to the bones. Repetitive actions, such as walking or running, can cause inflammation and swelling in the tendons, which is called tendonitis. Because of how often the knees are used in everyday activities, such as walking, knee tendonitis is a fairly common condition.

If you have knee tendonitis, you may experience symptoms such as swelling, tightness, and a dull ache. Mobility of the knee may also be limited, but resting the knee often remedies this problem and reduces symptom severity.


Osteoarthritis is the most common type of arthritis and is most prevalent in athletes and individuals with occupations that require repetitive movements.

Some signs of developing osteoarthritis include pain, tenderness, and inflammation. In most cases, the pain will gradually increase, but for some individuals, the pain appears suddenly.

Runner’s Knee

Runner’s Knee is the common name for patellofemoral pain, and it received this name because it is most common in active adults, especially runners. Pain due to runner’s knee begins behind or around the kneecap, and often feels like a dull throbbing. The pain is most common in the location where the knee meets the thigh bone.

Some individuals with runner’s knee may notice that their knee pops and grinds, which can cause more painful symptoms.


Gout results from a buildup of uric acid in the body, and while it most commonly collects in the feet, it can affect both knees. Those most commonly affected by gout include postmenopausal women and middle-aged men.

Knee pain that appears suddenly and has not been an issue before may be the beginning of gout. In addition to intense pain where the uric acid has built up, gout also causes significant swelling. Those with gout are often affected by spurts of gout that last for a few days.


Between your joints reside fluid-filled sacs called bursae. Bursitis is an inflammation of these sacs, which can cause pain and swelling.

While bursitis of the knee is not the most common location for bursitis to affect, it can happen and is often induced by repeatedly bending the knee.

Infectious Arthritis

Infected arthritis occurs when the fluid surrounding the knee joint becomes infected. This condition requires immediate attention because if left untreated, it can become septic, which is a medical emergency and requires emergency surgery.

Symptoms of infectious arthritis include sudden pain in only one knee. Those at an increased risk of infectious arthritis have a history of gout, arthritis, or a weakened immune system.

Can Arthritis Start Suddenly?

Arthritis has symptoms of pain and stiffness in and around one or more joints. While arthritis gradually worsens over time, some may feel their symptoms develop suddenly, while others notice that they gradually develop over time. 

In addition, arthritis symptoms can come and go, and with each appearance, the pain may be sudden. So, while arthritis does not start suddenly, the symptoms may for some individuals.

Symptoms of Sudden Knee Pain Without Injury

Sudden knee pain may feel like a dull ache or intense pain. This pain may also be accompanied by swelling, tenderness, and inflammation.

In some cases, the knee pain may come and go, while it persists for days in others.

Treatment for Sudden Knee Pain Without Injury

For most causes of sudden knee pain without injury, such as runner’s knee, tendonitis, bursitis, and gout, easing the pain revolves around resting the joint.

Ice can be applied for 20 minutes at a time, multiple times a day, and this will help control swelling. Elevating the joint will also help aid in the healing process. If the pain is unbearable, your doctor may prescribe pain-relieving medication such as ibuprofen to help decrease inflammation and reduce your pain.

These treatments will help reduce immediate pain, but lifestyle changes may need to be implemented to prevent future flare-ups. Dietary changes may be needed, especially for those treating gout, and a doctor can further discuss if these changes are necessary. Physical therapy can help manage pain and reduce symptom severity.

For those with sudden knee pain due to osteoarthritis, treatment involves managing the symptoms since it is not a condition that can be cured. Possible treatments include:

  • physical therapy
  • pain medication
  • knee braces or other assistive devices
  • treatment with a TENs unit
  • dietary changes
  • quitting smoking
  • losing excess weight
  • corticosteroids

A total knee replacement may be recommended as a definitive treatment in some individuals.

Medication for Sudden Knee Pain

In most cases, the root of knee pain is inflammation. Because of this, non-steroidal anti-inflammatory drugs (NSAIDs), including ibuprofen, effectively reduce inflammation and ease the pain in the knee.

However, it is important to check with a doctor before taking these medicines, especially for those already taking other medications, as they may react negatively or cause complications in those with pre-existing medical conditions.

When to See a Doctor?

If icing, resting, and taking pain medicine do not ease your knee pain, or if it persists for a few days, it is worthwhile to visit a doctor to determine the cause of the knee pain.

If your knee pain is sudden and severe, and you have a history of gout, arthritis, or a weakened immune system, visit with a doctor immediately as this may be a sign of infected arthritis, and ignoring it can lead to sepsis.

Visit a doctor if your knee pain comes and goes, as they may be able to offer physical therapy or medication to help reduce the pain.

Get Help From an Online Doctor

For those times when you need to see a doctor, but your pain makes leaving your house challenging or unfavorable, an online doctor is a helpful service. With an online doctor, such as DrHouse, you can visit a doctor without having to put any extra stress on your knee.

In addition, with DrHouse, you can meet with a virtual doctor within 15 minutes, so you can quickly get an answer to what is causing your knee pain. In the case of infectious arthritis, which can become a dangerous condition if untreated, these timely appointments allow you to immediately seek the care you need.

Key Takeaways

Sudden knee pain can be concerning, especially when it occurs without any injury to the knee. Because of the mobility provided by the knee joint and the many parts that comprise it, it is more susceptible to injury and pain.

Some conditions affecting the knee have pain that comes and goes, whereas others persist and gradually worsen. Those at the highest risk of knee pain include those who commonly complete repetitive knee movements, such as athletes.

If you notice any sudden knee pain, there are various home remedies to help ease the pain. However, you need to visit a doctor to help rule out more serious conditions. If your knee pain is severe or won’t go away, be sure to visit a doctor. An online doctor such as DrHouse is an excellent resource to meet with a doctor within 15 minutes and discuss the potential causes of your knee pain.


Content on the DrHouse website is written by our medical content team and reviewed by qualified MDs, PhDs, NPs, and PharmDs. We follow strict content creation guidelines to ensure accurate medical information. However, this content is for informational purposes only and not a substitute for professional medical advice, diagnosis, or treatment. For more information read our medical disclaimer.

Always consult with your physician or other qualified health providers about medical concerns. Never disregard professional medical advice or delay seeking it based on what you read on this website.

If you are experiencing high fever (>103F/39.4C), shortness of breath, difficulty breathing, chest pain, heart palpitations, abnormal bruising, abnormal bleeding, extreme fatigue, dizziness, new weakness or paralysis, difficulty with speech, confusion, extreme pain in any body part, or inability to remain hydrated or keep down fluids or feel you may have any other life-threatening condition, please go to the emergency department or call 911 immediately.



on your schedule

Skip the unnecessary waiting room,
see a board-certified clinician now.

Start an Online Visit
Available in 50 states. No insurance needed.

Prescriptions as needed
Renew or get a new Rx.

On-demand virtual visits
See a clinician in 15 minutes.

24/7 care support
We are here to help you.

  • 1

    Download the DrHouse app.
    Set up your free account in a minute.

  • 2

    Start a visit with an online doctor. Wait time is less than 15 minutes.

  • 3

    Get an Rx from your preferred pharmacy. Pick up a Rx nearby or get it delivered to you.

Download our app