Gout flare-ups are triggered when uric acid crystals that have already formed in your joints provoke a sudden inflammatory response. The most common triggers include alcohol, high-purine foods, sugary drinks, dehydration, certain medications, surgery, and even cold temperatures. Most flares can be traced back to something that either raised your uric acid levels or disturbed crystals already sitting in the joint.
What Happens Inside the Joint During a Flare
Uric acid circulates in your blood, and when levels stay too high for too long, it forms tiny needle-shaped crystals called monosodium urate (MSU) crystals that settle into joints. These crystals can sit quietly for months or years. A flare begins when immune cells in the joint (macrophages) swallow those crystals, which then rupture the internal compartments of the cell, spilling enzymes and triggering a powerful inflammatory chain reaction. The end result is a flood of a signaling molecule called IL-1β, which recruits waves of white blood cells into the joint.
This is why gout flares feel so intensely painful and come on so fast, often peaking within 12 to 24 hours. The immune system is essentially treating the crystals like a foreign invader.
Alcohol, Especially in Larger Amounts
Alcohol is one of the most reliable triggers. It raises uric acid in two ways: your body produces more uric acid as it breaks down alcohol, and alcohol also impairs your kidneys’ ability to flush uric acid out. A study tracking recurrent gout attacks found that the risk of a flare increased with each additional drink consumed in the prior 48 hours, regardless of the type of alcohol.
Beer has long been singled out as especially risky because it contains purines on top of the alcohol itself. But when researchers adjusted for total alcohol intake, no single type of beverage (beer, wine, or spirits) stood out as worse than the others. The total amount of ethanol, rather than a specific drink, appears to drive the risk. That said, even one or two drinks can be enough to set off a flare in someone whose uric acid is already borderline.
High-Purine Foods
Purines are compounds found in many foods that your body converts into uric acid. The highest-risk foods are organ meats like liver, kidney, and sweetbreads. Certain seafood, including anchovies, sardines, shellfish, and codfish, also ranks high. Red meat in large portions is another common culprit.
You don’t need to avoid all purines. Plant-based purine sources like lentils, spinach, and mushrooms have not been shown to carry the same flare risk. And moderate portions of fish are generally fine for most people with gout. The goal is to limit the concentrated sources, not to eliminate purines entirely.
Sugary Drinks and Fructose
Fructose is the only common sugar that directly produces uric acid during metabolism. When your body processes fructose, it rapidly burns through its energy currency (ATP), causing a buildup of compounds that get converted into uric acid. Worse, the uric acid produced then blocks an enzyme that would normally slow this cycle down, creating a feedback loop that generates even more uric acid.
The data on this is striking. Large prospective studies following over 125,000 people found that regular consumption of sugar-sweetened beverages was associated with a 208% increase in gout incidence. Even fruit juice carried a 77% increase, though the risk was lower than sodas and sweetened drinks. If you’re prone to flares, sugary drinks are one of the easiest triggers to eliminate.
Dehydration
When you’re low on fluids, the concentration of uric acid in your blood rises simply because there’s less water to dilute it. This pushes uric acid closer to (or past) the threshold where crystals form. The National Kidney Foundation specifically recommends that people with gout drink water at night, because crystal formation tends to increase during sleep when you go hours without fluids, your body temperature drops, and blood flow to extremities slows.
Hot weather, intense exercise, illness with fever or vomiting, and drinking alcohol (which is dehydrating on its own) all compound this effect. Staying well hydrated won’t cure gout, but it removes one of the easiest conditions for crystals to form.
Certain Medications
Diuretics, commonly prescribed for high blood pressure and heart failure, are a well-known trigger. These drugs work by making your kidneys excrete more water, but in the process they reduce the kidney’s ability to secrete uric acid. The mechanism is indirect: the fluid loss caused by diuretics appears to impair the kidney’s uric acid transport system, leading to a buildup in the blood.
Low-dose aspirin also reduces uric acid excretion. If you take either of these medications and notice more frequent flares, it’s worth discussing alternatives with your doctor rather than stopping them on your own, since they’re typically prescribed for serious conditions.
Cold Temperatures and Why the Big Toe
Gout famously strikes the base of the big toe, and temperature is a major reason. The joint at the base of the big toe sits at roughly 32°C (about 90°F), well below your core body temperature of 37°C. That difference matters because uric acid becomes less soluble as temperature drops. A decrease from 37°C to 35°C is enough to reduce the solubility threshold from 6.8 mg/dL to 6.0 mg/dL. In the cooler environment of your feet, ankles, and hands, crystals form more easily.
Research has also shown that lower temperatures don’t just promote crystal formation. They also amplify the inflammatory response itself, increasing the amount of IL-1β released when immune cells encounter those crystals. This double effect (more crystals forming plus a stronger reaction to them) helps explain why flares so often hit extremities and why some people notice more attacks in cold weather or after their feet get cold at night.
Surgery, Injury, and Physical Stress
Surgery is a potent but often overlooked trigger. In one study of patients who had knee replacement surgery, 53.8% of those with a history of gout experienced a flare within two years of the procedure, compared to just 3.6% of those without gout. The stress of surgery causes fluid shifts, tissue damage, and changes in blood flow that can both raise uric acid levels and disturb crystal deposits that were previously stable.
Joint injuries, even minor ones, can trigger a similar response by physically disrupting crystals in the affected area. Intense exercise or sudden increases in physical activity can do the same, especially if combined with dehydration.
Rapid Changes in Uric Acid Levels
One of the more counterintuitive triggers: flares can happen when uric acid drops quickly, not just when it rises. This is why people sometimes experience a flare shortly after starting uric acid-lowering medication. When uric acid levels shift rapidly in either direction, existing crystal deposits can become unstable, partially dissolve, or shed into the joint space, provoking the immune response all over again.
This is also why crash dieting or fasting can trigger flares. Rapid weight loss breaks down cells quickly, releasing purines, while simultaneously producing ketones that compete with uric acid for excretion through the kidneys. The current American College of Rheumatology guideline recommends maintaining serum urate below 6 mg/dL to gradually dissolve existing crystals and prevent new ones, but getting there slowly and steadily is key to avoiding flares during treatment.
Putting the Triggers Together
In practice, flares rarely come from a single trigger in isolation. A typical scenario might involve a weekend with heavier-than-usual drinking, a rich meal, not enough water, and a late night where your feet got cold under the covers. Each factor nudges uric acid levels up or makes crystallization more likely, and together they cross the threshold. Tracking your flares alongside what you ate, drank, and did in the 24 to 48 hours beforehand can help you identify your personal pattern and figure out which triggers matter most for you.