The Benefits of Prilocaine for Nerve Blocks

18 November 2025 15 Comments Joe Lindley

When you need a nerve block, the choice of anesthetic matters. Not all local anesthetics are built the same. Prilocaine stands out for its safety profile, especially when you’re looking for a reliable option with fewer side effects. Unlike lidocaine or bupivacaine, prilocaine doesn’t carry the same risk of serious heart or nerve toxicity at standard doses. That’s why it’s increasingly used in dental procedures, IV regional anesthesia, and even minor surgical nerve blocks where precision and safety are key.

How Prilocaine Works in Nerve Blocks

Prilocaine blocks sodium channels in nerve cells, stopping pain signals before they reach your brain. It starts working in about 5 to 10 minutes and lasts between 1 to 2 hours-long enough for most minor procedures but short enough to reduce lingering numbness. What makes it different is how quickly your body breaks it down. Prilocaine is metabolized in the liver and kidneys, and its main byproduct, ortho-toluidine, is less likely to cause methemoglobinemia than other anesthetics when used correctly.

It’s often mixed with epinephrine to prolong its effect and reduce bleeding at the injection site. In dental nerve blocks, for example, a 3% solution of prilocaine with epinephrine gives patients solid numbness without the jittery side effects you sometimes get with higher doses of lidocaine.

Why Prilocaine Is Safer for Many Patients

One of the biggest advantages of prilocaine is its lower toxicity. Studies from the Journal of Clinical Anesthesia show that prilocaine has a higher therapeutic index than lidocaine-meaning there’s a wider gap between the effective dose and the toxic dose. That’s critical in situations where you can’t precisely control how much anesthetic enters the bloodstream, like in finger blocks or when multiple injections are needed.

Patients with liver disease, older adults, or those on multiple medications often tolerate prilocaine better. It doesn’t interact badly with common heart medications like beta-blockers, and it doesn’t cause the same level of vasodilation that can lead to rapid absorption and overdose. In fact, the FDA has approved prilocaine for use in pregnant women for dental procedures, a category where many other anesthetics are used with caution.

Lower Risk of Methemoglobinemia-But It’s Still Possible

Prilocaine’s biggest drawback is its potential to cause methemoglobinemia, a rare condition where red blood cells can’t carry oxygen properly. But here’s the key: it only happens with high doses or repeated use. A single nerve block using standard doses (under 400 mg in adults) carries almost no risk. The real danger comes from using prilocaine cream for large areas of skin-like in laser hair removal or tattoo removal-where hundreds of milligrams can be absorbed.

For nerve blocks, you’re typically using 10 to 50 mg per injection. At that level, methemoglobinemia is extremely rare. Clinics that use prilocaine for pediatric nerve blocks or in patients with a history of anemia still prefer it over alternatives because the benefit outweighs the risk when dosed properly.

Hand with prilocaine injections and safety symbols, contrasting with high-toxicity warning

Prilocaine vs. Other Local Anesthetics

Comparing prilocaine to other options helps explain why it’s chosen in specific cases:

Comparison of Common Nerve Block Anesthetics
Anesthetic	Onset Time	Duration	Toxicity Risk	Methemoglobinemia Risk
Prilocaine	5-10 min	1-2 hours	Low	Very low (at standard doses)
Lidocaine	2-5 min	1-2 hours	Medium	None
Bupivacaine	10-20 min	4-8 hours	High	None
Ropivacaine	10-15 min	3-6 hours	Medium	None

Prilocaine doesn’t last as long as bupivacaine, so it’s not ideal for major surgeries. But for outpatient procedures-like removing a cyst, repairing a finger laceration, or dental work-it’s often the best middle ground. It’s faster than ropivacaine and safer than lidocaine for patients with heart conditions.

Real-World Use Cases

Prilocaine is the go-to anesthetic in many emergency departments for hand and finger blocks. Why? Because you can inject it near the wrist or base of the finger without worrying about accidental intravascular injection. If you hit a small artery, the risk of systemic toxicity is much lower than with lidocaine.

In dentistry, 3% prilocaine with 1:200,000 epinephrine is the standard for inferior alveolar nerve blocks. It gives complete numbness of the lower jaw and teeth without the prolonged numbness or tingling that some patients report with lidocaine. Parents of young children often prefer it because kids wake up faster and don’t chew their lips or tongue afterward.

Even in outpatient plastic surgery, prilocaine is used for tumescent anesthesia in minor liposuction or skin grafts. Its low tissue irritation and minimal systemic absorption make it ideal for areas with lots of small blood vessels.

Emergency clinician injecting prilocaine for finger repair with oxygen transport visualization

Who Should Avoid Prilocaine?

Prilocaine isn’t for everyone. You should avoid it if you’ve had a previous allergic reaction to amide-type anesthetics (though true allergies are rare). Also, people with severe G6PD deficiency-where red blood cells break down too easily-should be cautious, as prilocaine can trigger hemolysis in these cases.

Patients on nitroglycerin or other nitrates should also be monitored. The combination can increase the risk of low blood pressure, especially if epinephrine is added. And while prilocaine is generally safe in pregnancy, it’s still best to use the lowest effective dose.

How to Maximize Safety During Use

Here’s what works in real clinical practice:

Always aspirate before injecting-pull back on the syringe plunger to check for blood. This avoids accidental IV injection.
Use the smallest effective dose. For most nerve blocks, 20-50 mg is enough.
Never exceed 400 mg total in a single session for an adult.
Watch for signs of methemoglobinemia: blue-tinged skin, shortness of breath, headache, confusion. If seen, treat with methylene blue immediately.
For children, weight-based dosing is critical. Use 4 mg/kg as the maximum safe dose.

Most providers who use prilocaine regularly say the same thing: it’s predictable. You know what you’re getting. No surprises. No sudden drops in blood pressure. No prolonged numbness that lasts all day.

What’s the Future for Prilocaine?

Even with newer anesthetics like levobupivacaine and articaine gaining ground, prilocaine hasn’t been replaced. It’s still listed in the WHO Model List of Essential Medicines. That’s because it fills a unique niche: safe, effective, affordable, and easy to store.

Research is now looking at combining prilocaine with newer adjuvants like dexmedetomidine to extend its duration without increasing toxicity. Early trials show promise for longer-lasting nerve blocks in chronic pain management, especially for patients who can’t tolerate opioids.

For now, if you need a nerve block and safety is your top concern-whether you’re a patient or a provider-prilocaine remains one of the most reliable choices on the shelf.

Is prilocaine better than lidocaine for nerve blocks?

Prilocaine is often safer than lidocaine, especially for patients with heart conditions or those needing multiple injections. It has a lower risk of toxicity and doesn’t cause the same level of vasodilation, which means slower absorption into the bloodstream. However, lidocaine works faster and is more widely available. For most routine nerve blocks, prilocaine is preferred when safety is prioritized over speed.

Can prilocaine cause nerve damage?

Prilocaine itself doesn’t damage nerves. Like all local anesthetics, nerve injury from a nerve block is almost always due to the needle or injection pressure-not the drug. Proper technique, avoiding direct injection into a nerve, and using ultrasound guidance when possible reduce this risk significantly. Prilocaine is no more likely to cause nerve damage than lidocaine or bupivacaine.

How long does prilocaine last in a nerve block?

Prilocaine typically lasts 1 to 2 hours when used alone, and up to 3 hours when mixed with epinephrine. This makes it ideal for short procedures like dental work, minor skin surgeries, or finger repairs. It doesn’t last as long as bupivacaine, so it’s not used for post-op pain lasting more than a few hours.

Is prilocaine safe during pregnancy?

Yes, prilocaine is considered safe for use in pregnant women, especially for dental procedures. The FDA classifies it as Category B, meaning animal studies show no risk and human data supports its safety in low doses. As with any medication, use the lowest effective dose and avoid unnecessary injections.

What are the signs of prilocaine overdose?

Signs include ringing in the ears, metallic taste, dizziness, muscle twitching, seizures, and low blood pressure. In rare cases, it can cause methemoglobinemia, which shows up as bluish skin or lips and trouble breathing. If you suspect an overdose, stop the injection immediately and seek medical help. Treatment may include oxygen, IV fluids, or methylene blue for methemoglobinemia.

If you’re scheduled for a procedure involving a nerve block, ask your provider if prilocaine is an option. For many people, it’s the quiet hero of local anesthesia-less flashy than the alternatives, but far more dependable when it counts.