How To Prevent Decompression Sickness While Diving?

Decompression sickness happens when dissolved nitrogen comes out of solution as bubbles in your blood and tissues. The single most effective way to prevent it is to stay within the no-decompression limits for your depth and time, ascend slowly, and never skip a safety stop. Following your dive computer or tables, avoiding alcohol before diving, staying hydrated, and not flying too soon after your last dive all lower your risk further.

Decompression sickness — often called “the bends” — is a real injury, not a badge of toughness. It is largely preventable, and most prevention comes down to a handful of habits that experienced divers follow on every dive. This guide explains what is actually happening in your body, what the evidence supports, and where common advice gets shaky.

What Actually Causes Decompression Sickness?

Under pressure at depth, your body absorbs extra nitrogen from the air you breathe. The deeper you go and the longer you stay, the more nitrogen dissolves into your blood and tissues.

When you ascend, that pressure drops. If you come up slowly enough, the excess nitrogen travels to your lungs and leaves your body as you exhale. If you ascend too fast, the nitrogen can form bubbles in your bloodstream and tissues instead. Those bubbles are what cause decompression sickness.

This is the same principle as opening a bottle of soda. The gas stays dissolved under pressure. Release the pressure too quickly and it fizzes. Your body works the same way.

Bubbles can block blood flow and press on tissues. Symptoms usually appear within an hour of surfacing, though they can be delayed. Common signs include joint pain, dizziness, fatigue, tingling, and skin rashes. More serious cases affect the brain, spinal cord, lungs, or heart. Symptoms that appear after a dive should always be treated as a medical emergency until proven otherwise.

How To Prevent Decompression Sickness While Diving?

Prevention rests on controlling your exposure to nitrogen and giving your body time to release it. No single step guarantees safety, but stacking these habits dramatically lowers your risk.

Stay within your limits. Use dive tables or a dive computer and respect the no-decompression limits for your depth. These limits are based on accepted decompression models, not guesswork. Pushing past them is the most common way divers get into trouble.

Ascend slowly. A widely taught maximum ascent rate is 30 feet (9 meters) per minute, though many computers and training agencies recommend slower rates. Slower is better. Your computer will warn you if you climb too fast — pay attention to it.

Make a safety stop. A stop of about 3 to 5 minutes at 15 to 20 feet (roughly 5 to 6 meters) before surfacing is standard practice on most recreational dives. It is not a cure-all, and the evidence for its exact benefit is not airtight, but the practice is nearly universal because it adds a margin of safety.

Do a safety stop even on shallow dives. Many divers skip it on short, shallow dives. That is a judgment call, but the habit of always stopping keeps you consistent when it matters.

Keep your deepest dive first. On multi-dive days, plan your deepest dive early. Repeated dives at increasing depth add nitrogen load in a way that raises risk.

Take surface intervals seriously. Give yourself adequate time at the surface between dives. Your computer tracks your residual nitrogen — trust it over how you feel.

Hydrate and avoid alcohol. Dehydration and alcohol both appear to increase risk, though the evidence is not as strong as for depth and ascent rate. Still, avoiding alcohol before diving and drinking water throughout the day is sensible and low-cost.

Don’t dive when you’re sick or exhausted. Fatigue and illness can mask symptoms and affect your judgment. Skip the dive.

Why Does Flying Too Soon After Diving Increase Risk?

Flying exposes you to lower cabin pressure, which can trigger bubbles even after a dive that seemed fine. The pressure at altitude is lower than at sea level, so nitrogen that is still dissolved in your body can come out of solution during the flight.

The standard guidance is to wait at least 12 to 18 hours after a single no-decompression dive before flying, and longer — often 18 to 24 hours — after multiple dives or multiple days of diving. If you have used a dive computer, follow its suggested no-fly time. If you did any decompression diving, wait longer.

This is one of the most important and most overlooked rules. Divers who feel completely fine on the boat can still develop symptoms at altitude. The wait times come from established diving medicine guidance, not from marketing.

Does Your Dive Computer Make You Safer?

A modern dive computer is the best single tool most recreational divers have for managing decompression risk. It tracks your depth, time, ascent rate, and residual nitrogen in real time and adjusts its guidance based on your actual dive profile.

But a computer is only as good as the diver using it. It will not stop you from diving a profile that is too aggressive. It will not fix dehydration or a hangover. And it cannot account for individual factors like your age, fitness, or how your body handles nitrogen.

Dive computers use algorithms based on population-level models. That means they are built to keep most divers safe most of the time, not to guarantee safety for you personally. Treat your computer as a guide, not a permission slip.

What Individual Factors Raise Your Risk?

Two divers can follow the same profile and have different outcomes. That is because decompression sickness depends partly on factors specific to you.

• Age — risk appears to rise with age, likely due to changes in circulation and tissue composition.
• Body composition — higher body fat may increase nitrogen absorption, since fat holds nitrogen differently than muscle.
• Hydration — dehydration is widely thought to raise risk, though the evidence is not definitive.
• Alcohol — drinking before or between dives is associated with higher risk.
• Fatigue and poor sleep — both can affect judgment and possibly your body’s ability to handle stress.
• Illness or injury — diving while sick or recovering raises risk.
• Patent foramen ovale (PFO) — a small hole in the heart present in a significant share of the population. Some research links PFO to certain types of decompression sickness, particularly when symptoms involve the brain. The evidence is not settled, and screening every diver is not standard practice.

None of these factors means you cannot dive. They mean you should be more conservative with your profiles. If you have a known heart condition or a history of decompression sickness, talk with a diving medicine physician before your next dive.

What Should You Do If You Suspect Decompression Sickness?

Stop diving immediately. Get on 100 percent oxygen if it is available. Lie down and stay still. Call for emergency help and get to a hyperbaric chamber as soon as possible.

Do not try to “walk it off” or wait to see if symptoms improve. Early treatment with hyperbaric oxygen is the standard of care, and delays can worsen outcomes. Even mild symptoms like a rash or unusual fatigue after a dive deserve prompt attention.

Do not re-enter the water to try to “recompress” yourself. That is dangerous and not a substitute for proper medical care.

What the Evidence Does and Doesn’t Support

The core principles of decompression prevention — staying within limits, ascending slowly, and waiting before flying — rest on decades of diving physiology research and established clinical guidance. These are not controversial.

Other advice is less certain. The exact benefit of a safety stop on very shallow dives is debated. The role of hydration is widely accepted but not strongly proven in controlled trials. PFO screening is a topic of ongoing discussion among diving medicine specialists.

What is clear: the biggest risk factor is diving beyond your limits or ascending too fast. Get those right, and you have removed most of the danger. The rest is margin.