Tendonitis heals best when you stop doing the things that irritate the tendon, but knowing exactly what to cut out goes well beyond “just rest it.” Certain exercises, workplace habits, medications, sleep positions, and even dietary choices can slow your recovery or make the problem worse. Here’s what to avoid and why it matters.
High-Impact and Forceful Movements
Any movement that loads the affected tendon with sudden force is likely to aggravate tendonitis. Forceful, explosive motions like sprinting, jumping, or throwing a fastball put enormous stress on tendons that are already inflamed. Unnatural joint positions, like the overhead motion of a tennis serve or painting a ceiling, are equally problematic for shoulder tendons. If the activity that caused your tendonitis in the first place involves repetitive force or awkward positioning, continuing it (even at reduced intensity) will keep the cycle of irritation going.
Heavy weightlifting is a common culprit. Exercises that place the tendon under load at extreme ranges of motion, such as deep squats for patellar tendonitis or overhead presses for rotator cuff problems, can make things significantly worse during a flare. That doesn’t mean you should avoid all exercise, but the type and timing matter enormously.
Complete Rest Is Also a Problem
One of the biggest mistakes people make with tendonitis is going fully sedentary. While it seems logical to stop moving entirely, research on tendon healing consistently shows that prolonged immobilization leads to worse outcomes. In animal studies, tendons immobilized for three weeks survived 70% fewer stress cycles before failing compared to tendons that were immobilized for just one week and then allowed to move. Longer immobilization also led to weaker gait and reduced force production in the affected limb.
What works better is “relative rest,” meaning you avoid the specific aggravating activity but continue moving in ways that don’t provoke pain. The goal is to protect the tendon from further irritation while still giving it the mechanical stimulus it needs to heal properly. Gentle, pain-free stretching is usually the first step. Hold stretches for at least 30 seconds without pushing into pain. Once you can stretch the area fully without discomfort, both passively and actively, that’s generally when you can start adding light strengthening exercises.
Repetitive Motions at Work
Your job may be the single biggest factor keeping your tendonitis alive. CDC-affiliated research found that people who perform highly repetitive, forceful hand and wrist tasks have a risk of tendonitis 29 times greater than people in low-repetition, low-force jobs. High-repetition work was defined as tasks with a cycle time under 30 seconds, or spending more than half the work cycle doing the same motion pattern. Assembly line workers in food production, for example, performed up to 25,000 hand cycles per workday.
Keyboard and mouse use is a well-documented trigger for wrist and forearm tendonitis. Repeated wrist flexion causes the finger tendons to press against surrounding structures, and doing this thousands of times a day creates chronic irritation. If you work at a computer, avoid resting your wrists on hard surfaces while typing, keeping your wrists bent upward or downward for extended periods, or gripping a mouse tightly. Small adjustments matter: slide objects instead of lifting them, use tools with cushioned grips, and take frequent breaks from repetitive hand motions.
Certain Medications
A class of antibiotics called fluoroquinolones (ciprofloxacin, levofloxacin, and moxifloxacin are the most common) carries a well-established risk of tendon damage. These drugs roughly triple the risk of Achilles tendon rupture, and the risk stays elevated for up to 60 days after you stop taking them. The FDA added a black box warning about this in 2008 and later restricted their use for minor infections when alternatives exist.
The risk becomes dramatically worse if you take fluoroquinolones alongside oral corticosteroids. That combination increases the risk of Achilles rupture by roughly 19 times. Older adults face the greatest absolute risk. If you have active tendonitis and your doctor prescribes an antibiotic for an unrelated infection, it’s worth mentioning your tendon problem so they can choose an alternative if appropriate.
Overusing Anti-Inflammatory Painkillers
Reaching for ibuprofen or naproxen when your tendon flares up is almost reflexive, but relying on these drugs long-term during recovery is more complicated than it seems. In lab studies, common anti-inflammatory painkillers consistently inhibit tendon cell growth and migration, which are both necessary for healing. One study found that when healthy runners took an anti-inflammatory before a marathon, their patellar tendons showed a complete shutdown of the collagen production that normally occurs in response to exercise.
That said, the clinical picture is nuanced. These drugs may reduce adhesion formation around tendons without significantly harming tensile strength, and short-term use for pain management during an acute flare is generally considered acceptable. The problem comes from using them continuously over weeks to mask pain while continuing the activity that caused the injury. If you need daily painkillers to get through your workouts or your job, that’s a sign the tendon isn’t recovering, not a sign the medication is working.
Alcohol
Alcohol appears to interfere with tendon health through its toxic effects on collagen production, the protein that gives tendons their structure and strength. Even moderate weekly alcohol consumption was associated with a 33% increased risk of Achilles tendon problems in one large analysis. For heavier drinkers (more than 13 drinks per week for men, more than 6 for women), the risk of rotator cuff tears increased by 70% to 90%.
If you’re actively recovering from tendonitis, cutting back on alcohol removes one source of interference with the collagen synthesis your tendon needs to repair itself. Clinical dietary interventions for tendon problems have specifically emphasized reducing alcohol while increasing fish, berries, fruits, vegetables, nuts, and whole grains.
Sleeping on the Affected Side
For shoulder tendonitis, your sleep position can quietly work against you every night. Sleeping on your side creates the highest pressure inside the shoulder joint compared to any other position. Research found that back sleeping produced significantly lower pressure in the space where rotator cuff tendons sit than either side or stomach sleeping. One study of patients with rotator cuff tears found that 52 out of 58 were side sleepers.
The theory is that hours of sustained compression during sleep reduces blood flow to the rotator cuff tendons, accelerating wear and interfering with repair. If you have shoulder tendonitis, sleeping on your back is the lowest-pressure option. If you’re a committed side sleeper, at minimum avoid sleeping on the affected shoulder. A pillow tucked under the arm of the injured side can help keep the shoulder in a less compressed position.
Ignoring Warning Signs of Something Worse
Tendonitis typically develops gradually, with pain and stiffness that are worst first thing in the morning and improve slightly as the tendon warms up. If your symptoms suddenly change character, that can signal a partial or complete tendon tear, which requires different treatment. The hallmarks of a rupture are distinct: an audible pop or snap, a sudden sensation of being kicked or struck (people commonly turn around expecting someone to be behind them), and an inability to push off the foot or rise onto the toes in the case of the Achilles.
With a complete rupture, a visible or palpable gap often develops along the tendon. Surprisingly, many people can still walk after a rupture, which leads some to assume it’s just a bad flare of their tendonitis. If you experience a sudden pop, a dramatic change in function, or new swelling that doesn’t match your usual pattern, that warrants prompt evaluation rather than continued home management.