Fibromyalgia flare-ups are temporary spikes in pain, fatigue, and other symptoms that can last anywhere from a few days to several weeks. They’re usually set off by identifiable triggers, and while the specific combination varies from person to person, the most common culprits fall into a handful of categories: physical overexertion, poor sleep, emotional stress, weather changes, illness, and certain foods.
Physical Overexertion and the “Boom and Bust” Cycle
One of the most reliable ways to trigger a flare is simply doing too much on a good day. This pattern is so common it has a name: the boom and bust cycle. On days when pain is low, you push hard to catch up on everything you’ve fallen behind on. Then you pay for it with days of increased pain and exhaustion. The CDC lists repeated physical stress, including repetitive joint strain from exercise, housework, or physical jobs, as a recognized trigger for symptom worsening.
The frustrating part is that the tasks causing flares are often mundane. Vacuuming, grocery shopping, yard work. These used to be quick and easy, which makes it psychologically hard to stop before they’re done. But overexerting yourself, even with light activity, can set off a systemic pain response that lasts well beyond the activity itself.
Sleep Disruption Lowers Your Pain Threshold
Sleep and fibromyalgia have a two-way relationship. Pain makes it harder to sleep, and poor sleep makes pain worse. People with fibromyalgia tend to wake up during the deeper stages of the sleep cycle and get less slow-wave sleep, the restorative phase your body needs to repair tissue and regulate pain signals. Sleep deprivation directly lowers your pain threshold, meaning stimuli that wouldn’t normally register as painful start to hurt.
This creates a vicious cycle. A few nights of disrupted sleep can trigger a flare, and the increased pain from that flare makes the next night’s sleep even worse. Anything that interferes with sleep quality, whether it’s a late screen session, an irregular schedule, caffeine, or a noisy environment, can be the first domino in a flare.
Emotional Stress and Mental Load
Stressful or traumatic events are among the most commonly reported flare triggers. Stress activates your body’s fight-or-flight system, which increases muscle tension and amplifies pain signaling. For someone with fibromyalgia, whose nervous system already processes pain signals abnormally, even moderate stress can push symptoms over the edge. This includes not just major life events but the cumulative weight of daily pressures: work deadlines, family conflict, financial worry, or the mental load of managing a chronic condition.
Weather Changes, Especially Dropping Pressure
If you feel worse when a storm rolls in, you’re not imagining it. A 2019 study of 48 fibromyalgia patients found that 40 of them reported higher pain on days when barometric pressure dropped. A larger 2020 study of over 10,500 people with chronic pain confirmed the association between falling pressure and increased pain scores over a 15-month tracking period.
Barometric pressure isn’t the only weather variable that matters. Higher humidity and colder temperatures are also linked to worse symptoms. The combination that tends to feel best: warm, dry weather with higher barometric pressure, less rain, and calm winds. You can’t control the weather, but tracking local pressure changes can help you anticipate rough days and plan accordingly.
Illness and Infection
Getting sick puts extra demands on your immune system, which can amplify the widespread inflammation and pain sensitivity that characterize fibromyalgia. Even a common cold or flu can set off a flare that outlasts the infection itself. Certain infections have a particularly strong association with fibromyalgia symptoms, including hepatitis C, hepatitis B, HIV, and Lyme disease. These don’t just trigger flares in people who already have fibromyalgia. They’ve been linked to the initial development of the condition in some cases.
Dietary Triggers
Some people with fibromyalgia notice flares after eating specific foods, particularly highly processed ones. Processed foods tend to be high in added sugar and unhealthy fats, both of which promote inflammation. The flavorings and preservatives common in packaged foods can also trigger sensitivities in some individuals. There’s no universal “fibromyalgia diet,” but keeping a food journal alongside a symptom log can help you identify your personal triggers. Common suspects include foods with added sugar, fried foods, and heavily preserved snack items.
Hormonal Shifts
Because fibromyalgia is significantly more common in women, hormones are a frequent suspect. Research on this is less clear-cut than you might expect. A study tracking pain thresholds across the menstrual cycle found that women with fibromyalgia consistently had lower pain thresholds than healthy women, but those thresholds didn’t fluctuate much with hormonal changes throughout the cycle. Estrogen, testosterone, and other reproductive hormones were similar between the groups. That said, many women do report symptom changes around their period or during menopause. The relationship may be more individual than universal, so tracking your symptoms alongside your cycle is still worth doing.
How to Reduce Flare Frequency With Pacing
The most effective strategy for preventing flares from overexertion is activity pacing, a method developed specifically to break the boom and bust cycle. The core idea is simple: alternate between set periods of activity and rest, regardless of how you feel in the moment. The University of Michigan’s fibromyalgia program outlines two approaches.
Time-based pacing means doing a task for a set amount of time, resting for a set amount of time, and repeating until the task is finished. You rest even if you’re not tired. You stop even if you’re not done. Goal-based pacing means breaking a task into small steps and taking a rest after completing each step, no matter how long it took.
To build your own pacing plan, start with a simple task like vacuuming one room. Estimate how long you can do it before risking a flare, then figure out how much rest your body needs afterward. Try this plan for three to four days. If you can do the task and still feel okay that day and the next, gradually increase your activity time and reduce your rest periods.
Two “danger times” to watch for: days when you feel good (the temptation to overdo it is strongest) and physical activities you enjoy, where it’s easy to lose track of how much you’ve done. Building in planned rest during these moments is what keeps a good day from becoming the trigger for a bad week.