Full guide to nitrogen narcosis
How to avoid Nitrogen Narcosis

Keep this level - Credit: Konstantin Karchevskiy


Most divers have heard of nitrogen narcosis - but what is it, how does it work, and what do you do about it?

Nitrogen Narcosis Definition

Nitrogen narcosis, or more accurately inert gas narcosis, is a condition that hits many divers when performing deeper dives. Typically it will start at around 30 meters(100 feet) of water.

What is nitrogen narcosis?

Commonly referred to as nitrogen narcosis, it is now often referred to by the more accurate name of inert gas narcosis. It has been found that other gasses than nitrogen can cause the narcosis effect.

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Some even argue that any gas that can be breathed, save for a few such as helium, and cause this effect.

Divers, in particular in the US, often refer to inert gas narcosis as “the martini effect” or “Martini’s Law” as the effect is supposedly comparable to drinking one dry martini on an empty stomach for every 10 meters/33 feet descended beyond the first 20 meters/66 feet.

Symptoms of nitrogen narcosis

Click the image to read about the Deepest dive ever made - Credit: Littlesam

Nitrogen Narcosis Symptoms

Symptoms of Nitrogen Narcosis include

  • Dizziness
  • Emotional reactions such lightheadedness
  • Elation
  • Euphoria
  • Anxiety

Severe cases may also cause debilitating inertia, blindness, unconsciousness, and maybe even death.

Who gets Nitrogen Narcosis?

Inert gas narcosis theoretically affects all divers descending below 20 meters/66 feet, though the severity of the narcosis varies greatly from diver to diver. And even from dive to dive. For reasons not entirely understood.

How to be a Safer Diver: Emergency Planning for Diving

With experience, divers can learn to manage and cope with the effects of inert gas narcosis, but it is not possible, as far as we know now, to develop an actual tolerance.

deep diving with nitrogen narcosis

Diver going deep - Credit: Jon Milnes

What causes Nitrogen Narcosis?

The full cause of inert gas narcosis isn’t fully understood, but it is believed that a number of breathable gases react with the body’s tissues, in particular with the lipid, or fat, tissues.

As our brains consist predominantly of lipid tissues, the effect is mostly felt here.

The effects increase in severity as depth is increased, with most divers beginning to feel some effect at around 30 meters/100 feet, and these symptoms becoming severe at around 40 meters/140 feet.

This is one of the reasons, along with decompression illness and the risk of oxygen toxicity, for most organizations setting the recreational diving limit at 40 meters/140 feet.

Nitrogen narcosis treatment?

The remedy is as simple as descending to a shallower depth, after which the symptoms will subside with no known long-term effects.

In most cases, the dive can be continued at the new, shallower depth.

However, due to the feeling of euphoria and elation often caused by the narcosis, the affected diver may not be able to make the assessment that they are affected. Therefore they will not themselves make the decision to decrease their depth.

Because of this, it is important that buddies look out for each other on deep dives, and watch for any erratic or uncommon behavior that may be a sign of inert gas narcosis.

If these are spotted, your dive buddy should urge the diver to decrease their depth, or guide him or her up to shallower waters.

Don’t go Deep Diving alone

Nitrogen narcosis is a potentially severe condition, but luckily easy to manage.

Read Deep Diving: Rules, Recommendations And Fun Facts

Divers who are new to deep diving should always do their first ventures into the deep with experienced buddies or dive instructor. Make sure someone can assist you in case of “Martini’s Law”, until you’ve develop your own coping mechanisms for it.

And of course, maximum recreational dive depths should always be observed.

Have you ever been affected by Nitrogen Narcosis? Tell us about your experience in the comments below.

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