An arthritis flare is a period when joint symptoms suddenly worsen, bringing increased pain, swelling, and stiffness that can last days to weeks. The international rheumatology community defines a flare as “a cluster of symptoms of sufficient duration and intensity to require initiation, change, or increase in therapy.” In practical terms, it means your joints go from manageable to miserable, often without obvious warning.
How a Flare Feels
The hallmark of a flare is a noticeable spike in pain and stiffness beyond your usual baseline. Joints may swell visibly, feel warm to the touch, and become difficult to move through their normal range. But flares aren’t always limited to the joints. Fatigue, general malaise, and even depression can be part of the picture, and sometimes these systemic symptoms dominate the flare more than any specific joint swelling or tenderness.
One of the trickiest things about flares is that they can announce themselves before the worst symptoms hit. Fatigue, a vague sense of feeling unwell, and low mood can precede obvious joint symptoms by days or even weeks. Recognizing these early signals gives you a window to adjust your activity, contact your care team, or modify treatment before the flare peaks.
Flares Differ by Type of Arthritis
Not all arthritis flares look the same. The type of arthritis you have shapes how a flare starts, where it hits, and how long the stiffness lasts.
Rheumatoid Arthritis
Rheumatoid arthritis is driven by the immune system attacking joint tissues, so flares tend to involve significant inflammation. Morning stiffness is a defining feature and typically lasts an hour or longer before it begins to ease. Flares most commonly target the hands, wrists, and feet, and they often affect the same joints on both sides of the body. Some flares begin not with joint pain but with flu-like symptoms: fatigue, fever, weakness, and minor aches that build over several weeks.
Osteoarthritis
Osteoarthritis flares stem from cartilage wearing down until bone grinds against bone. Morning stiffness is milder and usually resolves within a few minutes of moving around. Flares tend to develop more gradually and affect weight-bearing joints like the knees and hips, or the joints closest to the fingertips. Sitting or resting a joint for an hour or so can bring the stiffness back, but it clears again once you start moving.
Gout
Gout flares are caused by uric acid crystals building up in a joint, most often the big toe. They tend to come on fast, sometimes overnight, with intense pain, redness, and swelling in a single joint. Gout is typically diagnosed during a flare, when uric acid crystals are easiest to detect in joint fluid. Not everyone with high uric acid levels develops gout, but once you’ve had one flare, more are likely without treatment.
Common Triggers
Flares can seem to come out of nowhere, but several patterns emerge when researchers look at what sets them off.
Stress and sleep deprivation are among the most frequently reported triggers. Both ramp up the body’s inflammatory response, creating conditions where a flare is more likely to ignite. Illness or infection can do the same thing, temporarily overwhelming the immune system and destabilizing joints that were previously under control.
Overexertion is a common culprit, especially in osteoarthritis. A weekend of heavy gardening, a long hike, or simply pushing past your limits on a good day can provoke a flare in the days that follow.
Diet plays a role as well. Refined carbohydrates, fried foods, sugar-sweetened drinks, red meat, and processed meat are all associated with increased inflammation. For gout specifically, alcohol and purine-rich foods like organ meats and shellfish are well-established triggers.
Weather is the trigger people ask about most, and the evidence is real but modest. A large study of over 2,600 people with chronic pain found relationships between increased symptoms and higher humidity, lower atmospheric pressure, and higher wind speed. Another study across six European countries linked higher humidity with worsening pain and stiffness, especially in colder weather. The effects are consistent enough to be real, though researchers still can’t fully explain the biological mechanism behind them.
Medication changes are another trigger worth knowing about. Tapering or stopping anti-inflammatory medications, even under a doctor’s guidance, can unmask underlying disease activity and spark a flare.
Movement During a Flare
The instinct during a flare is to stop moving entirely, but complete rest can actually make stiffness worse. The Mayo Clinic recommends staying active even during flares, shifting to gentler forms of movement rather than stopping altogether. Range-of-motion exercises, where you slowly move each joint through its full arc without resistance, help maintain flexibility without stressing inflamed tissue. Exercising in water is another option, since buoyancy supports your joints while allowing you to move freely.
The key is scaling back intensity, not activity itself. If your usual routine includes walking or resistance training, a flare is the time to switch to stretching, gentle yoga, or a pool session. Once the flare subsides, you can gradually return to your normal level.
How Long Flares Last
There’s no single timeline. Some flares resolve in a day or two, particularly with prompt treatment adjustments. Others drag on for weeks, especially if they’re driven by an underlying change in disease activity rather than a one-time trigger. Rheumatoid arthritis flares tend to last longer than osteoarthritis flares, which often calm down once the triggering activity or weather pattern passes. Gout flares typically peak within 12 to 24 hours and can last up to two weeks without treatment, though medication can shorten that considerably.
Tracking your flares, including what preceded them, how long they lasted, and what helped, gives you and your care team better data for adjusting your treatment plan over time.
Red Flags That Need Immediate Attention
Most flares, while painful, aren’t emergencies. But certain symptoms during a flare signal something more serious. A fever above 101°F combined with nausea, chills, and severe joint pain and swelling could indicate septic arthritis, a joint infection that requires urgent treatment. Small red or black spots near the nails on your fingers or toes can indicate that blood vessel inflammation has caused tissue damage. Complete inability to move your hands or feet, sudden shortness of breath, or chest pain during a flare all warrant an emergency visit. Severe stomach pain is also worth taking seriously, since some arthritis medications can cause bleeding ulcers.