What Is Nitric Oxide? Can You Have Too Much or Too Little?

Nitric oxide (NO) is a tiny but powerful molecule that plays a critical role in keeping your body healthy. It acts as a signaling molecule, helping blood vessels relax and expand, improving blood flow, and supporting everything from heart health to exercise performance. But when it comes to nitric oxide levels, balance is key — and both too little and too much can cause problems.

What Happens if You Have Too Little Nitric Oxide?

Low nitric oxide levels can lead to poor circulation, higher blood pressure, fatigue, and even erectile dysfunction. Since NO is crucial for blood vessel dilation, not having enough makes it harder for oxygen and nutrients to reach your muscles, brain, and organs. This is one reason why boosting nitric oxide production is a major focus for athletes, people looking to improve cardiovascular health, and those aiming to enhance overall energy levels.

Can You Have Too Much Nitric Oxide?

When people hear about the benefits of nitric oxide, they often wonder: Can I just take tons of supplements like L-citrulline and L-arginine to boost my levels even more? The short answer: No, it doesn’t work like that.

Your body has built-in systems to tightly control nitric oxide production. Even if you take large amounts of nitric oxide boosters like citrulline or arginine, your body will only convert what it needs into nitric oxide — and the rest simply won't be processed. Flooding your system with supplements won't cause dangerously high nitric oxide levels through this pathway. It's a waste of money, not a risk of toxicity.

However, inhaling nitric oxide gas is another story. Medical-grade nitric oxide gas is sometimes used in hospitals for specific lung treatments, but inhaling it outside of a medical setting is extremely dangerous and poisonous.

The Bottom Line

• Low nitric oxide can hurt your circulation, heart health, and physical performance.

• Supplementing responsibly with precursors like citrulline or arginine can support healthy nitric oxide levels — but taking extra won't "overload" you.

• Inhaling nitric oxide gas is toxic and should never be done outside a medical setting.

Maintaining healthy nitric oxide production through smart supplementation, a diet rich in leafy greens and beets, and regular exercise is the safest and most effective way to keep your body running at its best.