Tendonitis

Tendonitis happens when tendons — the strong, fibrous cords that connect muscle to bone — become inflamed or irritated. This can result in pain and tenderness just outside a joint, particularly during movement. It can occur in any tendon in the body, but is most common around the shoulders, elbows, wrists, knees and heels, where certain tendons are subjected to repeated stress from everyday movement, work or sport.

Because tendons are involved in nearly every movement we make — reaching overhead, gripping a steering wheel, climbing stairs, typing at a desk — even a mild case of tendonitis can quickly interfere with daily life, work and the activities people enjoy most. It is one of the most common reasons people seek care for joint-area pain, affecting both dedicated athletes and people who have never set foot in a gym.

Recognising it early, and understanding what is actually happening inside the tendon, makes a meaningful difference to how quickly — and how completely — a person recovers.

Understanding Tendons and How Tendonitis Develops

Tendons are made of tough, fibrous collagen tissue arranged in a way that allows them to withstand considerable pulling force as muscles contract to move the joints. Unlike muscle, tendons have a relatively limited blood supply, which allows them to remain strong under load but also means they heal more slowly when injured.

Tendonitis typically develops when a tendon is subjected to repeated, low-grade stress — often through repetitive movement — faster than it can recover between uses. Over time, this can lead to small areas of irritation and inflammation within the tendon or its surrounding sheath. Less commonly, tendonitis can follow a single, more forceful strain or injury. Most tendonitis can be treated with rest, medication and physical therapy, without the need for surgery.

Common Types of Tendonitis by Location

While tendonitis can technically occur in any tendon, certain locations are affected often enough that they have their own well-recognised names.

Tennis Elbow (Outer Elbow): Often linked to pepetitive wrist extension and gripping, such as in racquet sports or manual work
Golfer's Elbow (Inner Elbow): Often linked to repetitive wrist flexion and gripping, such as in golf, throwing sports or manual labour
Rotator Cuff Tendonitis (Shoulder): Often linked to repetitive overhead movement, such as swimming, throwing or overhead lifting
Achilles Tendonitis (Back of the heel): Often linked to running, jumping, or a sudden increase in activity level or intensity
Patellar Tendonitis (Below the kneecap): Often linked to sports involving repetitive jumping, such as basketball and volleyball
De Quervain's Tenosynovitis (Wrist, at the base of the thumb): Repetitive thumb and wrist movement, such as texting, lifting a child, or certain manual tasks

If you are experiencing sudden or severe pain, and it happened during an accident or activity, you may have torn a tendon. Do seek medical attention if your symptoms do not get better after a few days or if they get in the way of your daily activities.

Symptoms of Tendonitis

Symptoms are often worse at the start of an activity, may ease slightly as the area warms up, and then return with rest or the following day. Sudden, severe pain that occurs during an accident or forceful activity, especially when accompanied by a noticeable loss of strength or an audible pop, is more suggestive of a tendon tear than straightforward tendonitis, and generally follows a different course and treatment path.

Common symptoms of tendonitis include:

Pain in a tendon and the surrounding area that worsens when you move
Difficulty moving the joint
Stiff joints
A grating or crackling sensation when you move the tendon
Swelling at the joint, often with skin discolouration

What Causes Tendonitis?

Tendonitis could be caused by repeating the same movement time after time, such as through activities like running or throwing, as it puts stress on the tendons and, over time, could result in tendonitis. It could also be caused by sudden injuries.

Certain chronic conditions may also cause tendonitis, such as:

Diabetes: Prolonged high blood sugar levels can cause changes to the structure and quality of collagen, the main protein that gives tendons their strength and elasticity. This can make tendons stiffer, less flexible, and more prone to irritation and injury, which is part of why tendon problems such as frozen shoulder and trigger finger are more common in people with diabetes.
Rheumatoid arthritis: This autoimmune condition causes the immune system to attack the lining of joints, but the inflammation it triggers frequently extends to nearby tendons as well, particularly in the hands, wrists and feet. Ongoing inflammation in and around the tendons can lead to tendonitis, and in more severe or longstanding cases, can weaken the tendon enough to increase the risk of rupture.
Gout: Gout occurs when uric acid crystals build up in and around joints, triggering sudden, intense inflammation. These crystals can also deposit in and around tendons, provoking a similar inflammatory response there — most commonly affecting the Achilles tendon — which can cause pain, swelling and tenderness that closely mimics standard tendonitis.
Osteoarthritis: As the cartilage within a joint wears down, the altered joint mechanics and bony changes that follow can place uneven or excessive stress on the tendons crossing that joint. Over time, this altered loading pattern can contribute to tendon irritation and inflammation, particularly in joints already affected by significant wear and tear.

Risk Factors for Tendonitis

Anyone could get tendonitis, however it is more common in those who perform repetitive actions, such as:

Sports such as tennis, golf or running
Shovelling
Painting
Scrubbing

Other risk factors include:

Poor posture
Medical conditions that may weaken your muscles
Age. Your tendons become more prone to wear and tear as you get older
Occupations involving repetitive manual tasks, vibration tools, or awkward joint positions sustained over many years
A sudden increase in the intensity, frequency or duration of an activity, without allowing the body time to adapt

How Tendonitis Can Progress

Left unaddressed, tendonitis does not always follow a simple, linear course, and understanding how it can evolve helps explain why early attention to symptoms matters.

Acute tendonitis: Pain and inflammation develop relatively quickly, often linked to a specific activity or a recent increase in activity level, and generally responds well to rest and conservative treatment
Chronic tendon changes: If the underlying overuse continues without adequate recovery, the tendon can undergo more chronic, degenerative changes (tendinosis), which tend to be more persistent and may take longer to resolve
Increased risk of tendon tear: In some cases, a tendon that has been chronically weakened by ongoing tendinosis becomes more vulnerable to a partial or complete tear, sometimes with a relatively minor additional strain

How is Tendonitis diagnosed?

Diagnosis of tendonitis usually begins with a history of the pain and its relationship to specific activities, along with a physical examination, and may be supported by imaging when the diagnosis is unclear or symptoms are more severe or persistent.

Physical Examination: Assessment of the affected area for tenderness, swelling, warmth and pain during specific movements or resisted muscle testing, which often points strongly to the diagnosis on its own.
X-ray: Does not show tendons directly, but can help rule out other causes of pain, such as a fracture or arthritis, and may show calcium deposits sometimes associated with chronic tendon problems.
Ultrasound: Uses sound waves to directly visualise the tendon, showing thickening, tears, or signs of inflammation, and can be performed dynamically as the joint moves.
Magnetic Resonance Imaging (MRI): Provides detailed images of the tendon and surrounding soft tissue, useful for confirming the diagnosis, assessing severity, and distinguishing tendonitis from a partial or complete tendon tear.

How to Prevent Tendonitis

You can take the following steps to lower your chances of getting tendonitis:

Avoid staying in the same position for too long, take breaks every 30 minutes
Practise proper posture and body positions for all activities, including lifting heavy objects
Avoid using one hand to carry heavy objects
Properly stretch and warm up before starting an activity
Wear properly sized equipment and shoes
Stop any activities if you feel pain
Gradually increase the intensity, duration or frequency of a new activity rather than progressing too quickly
Incorporate regular strengthening exercises for the muscles supporting frequently used tendons, particularly if your work or sport involves repetitive movement

For the great majority of people, tendonitis is a manageable condition that improves well with a sensible combination of rest, targeted exercise and, where needed, medical treatment. Because tendons heal relatively slowly compared with other tissues, patience and consistency with a rehabilitation programme play a particularly important role in achieving a full and lasting recovery.

Understanding which tendon is involved, what is driving the irritation, and how to gradually rebuild its strength and tolerance to activity gives most patients a clear path back to pain-free movement and a reduced likelihood of the problem recurring.