Thiazide Diuretics and Gout: What You Need to Know About Uric Acid Risks

Many people take thiazide diuretics like hydrochlorothiazide (HCTZ) to control high blood pressure. It’s cheap, effective, and has been used for over 60 years. But if you’ve ever had gout-or know someone who has-you’ve probably heard a warning: thiazide diuretics can trigger gout flares. This isn’t just a side effect you might ignore. It’s a real, measurable risk that changes how you manage your health.

How Thiazide Diuretics Raise Uric Acid

Thiazide diuretics work by blocking sodium reabsorption in the kidneys. That means more water and salt leave your body, lowering blood pressure. But here’s the catch: they also mess with how your kidneys handle uric acid. Uric acid is a waste product from breaking down purines in food. Normally, your kidneys filter it out. But thiazides interfere with specific transporters-OAT1 and OAT4-that move uric acid out of the blood and into urine.

Instead of being flushed away, uric acid gets trapped in your bloodstream. Studies show serum uric acid levels can jump 6% to 21% within just 3 to 7 days of starting a thiazide. This isn’t a slow build-up. It’s fast. And it doesn’t go away unless you stop the drug. If your levels stay high for months, uric acid crystals can form in your joints-especially your big toe-and trigger a gout attack.

Who’s Most at Risk?

Not everyone on thiazides gets gout. But some people are far more likely to. If you already have high uric acid levels-over 7.0 mg/dL for men or 6.0 mg/dL for women-you’re in a high-risk group. So are people who’ve had even one gout flare in the past. The risk isn’t just about the drug. It’s about your body’s baseline.

Research from a 2024 study tracking over 247,000 people found that after 180 days of taking thiazides, the chance of needing gout medication jumped by 41%. That’s not a small number. It’s a turning point. And it’s why doctors now check uric acid levels before prescribing these drugs. The American College of Cardiology and American Heart Association recommend it.

Other factors stack the deck. Obesity, drinking alcohol, eating red meat or shellfish, and having kidney problems all raise your uric acid. If you’re on a thiazide and you’re doing any of those things, your risk multiplies.

Thiazides vs. Other Diuretics

Not all diuretics are the same when it comes to gout. Loop diuretics like furosemide are even more likely to trigger flares than thiazides. But among thiazides, there’s confusion. For years, people thought chlorthalidone was worse than hydrochlorothiazide. But a 2019 study found they carry nearly the same risk when given in similar doses.

Here’s the surprise: potassium-sparing diuretics like spironolactone don’t raise uric acid at all. That’s because they work differently. They block aldosterone, not sodium-chloride transporters. So if you have both high blood pressure and gout, spironolactone might be a better fit.

What Happens When You Get Gout on Thiazides?

There’s no difference between gout caused by thiazides and gout from any other cause. The pain is the same-sudden, intense, often in the big toe. The joint swells, turns red, and feels hot to the touch. Blood tests will show uric acid above 6.8 mg/dL, the point where crystals start forming.

The problem isn’t just the flare. It’s the chain reaction. Once you have one gout attack, you’re more likely to have more. And doctors often respond by prescribing colchicine or allopurinol to prevent future flares. But here’s the catch: those drugs cost more. In one study, nearly 19% of people on thiazides ended up needing gout medication within two years. That’s a lot of extra prescriptions, side effects, and costs.

What Should You Do?

If you’re on a thiazide and have never had gout, don’t panic. But do talk to your doctor. Ask if your uric acid level has been checked. If it hasn’t, get it tested. If your level is above 7.0 mg/dL, you might want to consider alternatives.

If you already have gout, thiazides aren’t the best choice. The European League Against Rheumatism says you shouldn’t use them as your main blood pressure drug if you have gout-unless you’re also taking urate-lowering therapy like allopurinol.

Good alternatives exist. Losartan, a blood pressure pill in the ARB class, actually helps your kidneys flush out uric acid. Calcium channel blockers like amlodipine don’t raise uric acid either. They’re not always cheaper than generic thiazides, but they’re safer for your joints.

Lifestyle Matters-More Than You Think

Medication isn’t the whole story. Diet and habits play a huge role. Alcohol, especially beer and spirits, spikes uric acid. Red meat, organ meats, and shellfish are loaded with purines. Even sugary drinks-especially those with fructose-can trigger flares.

Weight loss helps. Losing just 5-10% of your body weight can cut uric acid levels significantly. Drinking more water-aim for 2 to 3 liters a day-helps your kidneys flush out the crystals before they settle in your joints.

The European guidelines say your target uric acid level should be below 6.0 mg/dL if you have gout. That’s lower than most people think. It’s not enough to just treat the pain. You need to treat the cause.

The Bigger Picture: Benefits vs. Risks

Thiazide diuretics are still one of the most prescribed blood pressure drugs in the world. In the U.S. alone, over 35 million prescriptions were filled in 2022. Why? Because they work. They cut stroke and heart attack risk in people with high blood pressure. For someone with no history of gout, the benefits often outweigh the risks.

But that calculus changes if you’ve had a gout flare. Then, the risk isn’t just a side effect-it’s a trigger for chronic pain, joint damage, and long-term disability. That’s why smart doctors now screen for it. That’s why guidelines have changed. That’s why alternatives exist.

It’s not about avoiding thiazides entirely. It’s about using them wisely. Test first. Monitor often. Choose alternatives when needed. And never ignore a swollen toe.