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

If you're taking a thiazide diuretic like hydrochlorothiazide (HCTZ) for high blood pressure, you might not realize it could be raising your risk of gout. This isn't a rare side effect-it's well-documented, predictable, and happens in a significant number of people. About 12% to 15% of patients on these medications develop higher-than-normal uric acid levels. And while only 1% to 2% go on to have actual gout attacks, that’s still a meaningful number given how widely these drugs are prescribed-over 35 million HCTZ prescriptions were filled in the U.S. in 2022 alone.

How Thiazide Diuretics Raise Uric Acid

Thiazide diuretics work by blocking sodium reabsorption in the kidney’s distal tubule. That helps reduce fluid volume and lowers blood pressure. But here’s the catch: they also interfere with how the kidneys handle uric acid. Uric acid is a waste product that normally gets filtered out and excreted in urine. But thiazides mess with the transporters that move uric acid out of the blood and into the urine.

Specifically, they compete with uric acid for the same transporters in the kidney-OAT1 and OAT4. When thiazides bind to these transporters, they push uric acid back into the bloodstream instead of letting it leave the body. This isn’t a minor bump in levels. Studies show serum uric acid can rise by 6% to 21% within just 3 to 7 days of starting the medication. And it doesn’t go away after a few weeks-it stays elevated as long as you’re taking the drug.

This mechanism is why even low doses matter. You don’t need to be on high-dose HCTZ to see this effect. A 12.5 mg or 25 mg daily dose is enough to trigger the change. And if you already have high uric acid or a history of gout, you’re at higher risk.

Who’s Most at Risk?

Not everyone on thiazides gets gout. But certain people are much more likely to. If you have:

• Serum uric acid above 7.0 mg/dL (men) or 6.0 mg/dL (women)
• A past episode of gout
• Chronic kidney disease
• Obesity or a diet high in red meat, seafood, or alcohol

...then you’re in the high-risk group. The risk also climbs the longer you take the drug. A 2024 study tracking over 247,000 people found that the chance of needing gout medication jumped from 18% after 30 days to 41% after more than 180 days of thiazide use. That’s not a coincidence-it’s a pattern.

What’s more, gout attacks triggered by thiazides look exactly like any other gout attack: sudden, intense pain in the big toe, swelling, redness, warmth. The joint inflammation doesn’t care if the cause is diet, genetics, or a pill-it just hurts.

Thiazides vs. Other Diuretics

Not all diuretics are the same when it comes to uric acid. Loop diuretics like furosemide (Lasix) are even more likely to raise uric acid levels than thiazides. But among thiazides, there’s been confusion about whether chlorthalidone is worse than hydrochlorothiazide. Recent data says no-both carry similar risks at equivalent doses. Earlier assumptions that chlorthalidone was riskier weren’t backed up by real-world outcomes.

On the flip side, potassium-sparing diuretics like spironolactone don’t raise uric acid at all. That’s important because if you need a diuretic and have gout, spironolactone is a viable alternative. It’s often used in heart failure or resistant hypertension, and it doesn’t trigger the same transporter conflict in the kidney.

What Should You Do?

If you’re on a thiazide diuretic and haven’t had gout, don’t panic. But do talk to your doctor about checking your uric acid level-especially if you’ve had joint pain in the past. The American College of Cardiology and American Heart Association recommend measuring uric acid before starting thiazides in people with a history of gout or hyperuricemia. Yet, studies show only about 85% of doctors actually do this.

If your uric acid is high and you’re still on the drug, your doctor might consider:

• Switching to an alternative antihypertensive with a neutral or even beneficial effect on uric acid
• Adding a urate-lowering medication like allopurinol (starting at 100 mg daily)
• Trying a different class of blood pressure medication altogether

Losartan (Cozaar), an ARB used for high blood pressure, actually helps lower uric acid by blocking the URAT1 transporter that reabsorbs urate in the kidney. Calcium channel blockers like amlodipine also don’t raise uric acid. These options may cost more than generic HCTZ-about 25% to 30% more based on 2023 Medicare pricing-but for someone with gout, the trade-off can be worth it.

What About Lifestyle?

Medication isn’t the whole story. Diet and habits matter just as much. Alcohol-especially beer and spirits-increases uric acid production and reduces its excretion. Purine-rich foods like organ meats, shellfish, and certain fish do the same. Even sugary drinks with high-fructose corn syrup can trigger spikes.

The European League Against Rheumatism recommends keeping serum uric acid below 6.0 mg/dL for people with gout. That’s lower than the old target of 6.8 mg/dL (the saturation point). Achieving that often means combining medication with lifestyle changes: reducing alcohol, cutting back on red meat, drinking more water, and losing weight if needed.

When to Be Concerned

You should be concerned if:

• You start feeling sudden, severe pain in one joint-especially your big toe
• You’ve had a gout attack before and are now on a thiazide
• Your uric acid level was normal before starting the drug, but it’s now above 7.0 mg/dL
• You’ve been on the drug for more than 6 months and haven’t had your levels checked

Don’t wait for a flare-up to act. Once gout starts, it often comes back. And each attack can damage joints over time.

The Bigger Picture

Thiazide diuretics are cheap, effective, and have saved millions of lives by reducing strokes and heart attacks in people with high blood pressure. That’s why major guidelines still recommend them as first-line treatment for uncomplicated hypertension. But medicine isn’t one-size-fits-all. What works for one person might cause harm to another.

The key is awareness. If you have gout or high uric acid, your doctor should know. And if you’re on a thiazide and have no idea your uric acid is climbing, you’re missing a chance to prevent something painful and preventable.

There’s hope on the horizon too. A new class of diuretics is being tested in clinical trials-selective sodium-chloride cotransporter inhibitors designed to lower blood pressure without messing with uric acid transporters. Results aren’t expected until late 2025, but they could change how we treat hypertension in people with gout.

For now, the best strategy is simple: know your numbers, ask questions, and don’t assume a common medication is harmless just because it’s widely used.