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What Causes Decompression Sickness?

When you first get started in the world of diving, one thing that you’ll immediately be told is that you have to do certain things in order to avoid “the bends.” The bends are essentially decompression sickness, which can be incredibly dangerous to you. In some cases, it can even be fatal – which die if you aren’t careful! This is definitely not something you want to do or experience. Decompression sickness isn’t fun, and if you aren’t careful, you can cause permanent damage to your body to the point that you may not even be able to dive ever again. It is not something you or anyone else wants, especially if you’ve just fallen in love with diving! But what causes decompression sickness, exactly?

Whether you are new to the world of scuba diving, or if you’re already experienced in it, you’ve probably already heard about the bends (or decompression sickness or DCS). But you might not know exactly what it is, or you may have an idea, but you aren’t quite sure. However, the truth is that if you want to be spending a significant amount of time underwater and diving down to the deep, you should know. It’s important for you (and every diver) to be aware of the dangers of decompression sickness. That way, you can seek treatment immediately if you feel that you have it.

DCS is pretty scary if it’s severe enough, and as we said, it can kill you. So, in today’s article, we are going to talk about everything you need to know about The Bends. We’ll discuss the symptoms of decompression sickness, as well as the possible effects and consequences it may have. And, of course, we will find the answers to the question “what is decompression sickness?”

Let’s get started!

What’s DCS or Decompression Sickness, Exactly?

what causes decompression sickness

There are a number of different names by which decompression sickness goes. You’ll hear it referred to as, yes, the bends, but also by DCS, Caisson disease, or even divers’ sickness. DCS is basically what happens to a diver when bubbles of nitrogen get built up inside the body. This sickness occurs when the bubbles don’t dissolve properly before the diver resurfaces; if a diver comes down with The Bends’ case, many irritating symptoms that can range from inconvenient to severe.

You may be asking why decompression sickness gets called The Bends. Well, this term is basically an informal, colloquial phrase that people use because of the joint pain that often gets associated with DCS. Joint pain is just one of the many symptoms that you will experience if you find yourself dealing with a case of DCS.

There are actually a few different types of decompression sickness – all of which we will be discussing, of course. But first, let’s answer the question of the cause of this condition is.

What Causes Decompression Sickness?

It’s important to answer the question of what causes decompression sickness. That way, you can avoid these things and take the necessary steps to protect yourself from DCS. So, let’s get right to it, shall we?

What causes decompression sickness? Well, to answer this question, let’s take a look at what happens as a diver well… dives.

A diver begins to descend to the depths of the sea. As he does, the pressure begins to increase around his body. The result? Nitrogen gas begins to be absorbed by the body, into the tissues, and into the blood. There’s nothing bad about the body absorbing nitrogen into blood and tissue, as this isn’t harmful on its own. In fact, the body can absorb nitrogen pretty safely, at least to a certain extent. The problem lies in the diver’s ascent back to the surface.

You see if the diver begins his ascent and he does it a bit too fast, the quick change in pressure can cause an issue. This quick ascent does not give his body enough time to adjust to the change in pressure and for expelling the nitrogen that was absorbed safely. Ascend properly in scuba diving is very important and if not done properly the body begins to decompress.

During this decompression process, the dissolved nitrogen absorbed in the blood and tissues begins to revert back into a gaseous state before getting expelled from the body on the exhale. The problem is that this process is slow but steady, and it is typically relative to the depth and/or the length of the dive. The rapid reduction of the pressure around the diver’s body (like in the quick ascent) will cause the dissolved to gas transition in the blood and the tissues rather than in the lungs where it should happen. As a result, gas bubbles begin to form.

What Symptoms Do You Get with Decompression Sickness?

Now that we know what causes decompression sickness let’s take a look at the symptoms of DCS. One of the biggest and most prominent effects (or symptoms) that you will experience with DCS is abdominal pain. Another is joint pain (which is the origin of the term The Bends!). You’ll experience other general symptoms here as well, such as red rashes throughout your body, fatigue, numbness, vertigo, upset stomach, and even blurred vision.

There are actually a few different types of DCS, and a diver can suffer one or more simultaneously. Let’s take a look at these types to be better prepared when you go for your dives.

It may be wise to bookmark this page for easy reference if you’re worried that you are experiencing DCS. Of course, the best thing you can do is take yourself to the doctor if you suspect you’re dealing with the case of The Bends. If your symptoms are severe, go straight to the emergency room. Don’t hesitate. It could save your life.

DCS Type I

The first type of DCS, aptly named Type I, is the type that you should be least concerned about. This is because Type I is pretty much the least serious. It’s also not considered to be life-threatening at all (usually, at least). Typically, when you are experiencing a case of DCS Type I, you’ll be feeling some pain around your limbs and your joints. This is because of the nitrogen bubbles that are intensifying around your tendons and/or your bone marrow. However, note that Type I DCS can still manifest in your skin and in your lymphatic system.

Here are some of the symptoms you will likely experience.

  • Swelling
  • Itching
  • Fatigue
  • Skin Bends and/or Mottled Skin Appearance
  • The feeling that your skin might be crawling


The next type is Type II, which does comprise the most serious forms that decompression sickness takes. If you suffer from type II DCS, you may experience severe complications. Type II DCS is when the nitrogen bubbles begin to enter the body’s nervous system, and certain body parts start getting badly affected. If symptoms start and you don’t get treated, you can get paralyzed or even die. There are a few manifestations of this type of decompression sickness.

Pulmonary Decompression Sickness

This type of DCS occurs when the nitrogen bubbles begin to form in the lung’s capillaries. This results in not only respiratory issues but also heart issues. And if the gas gets forced into the vessels of the lungs, the diver can even suffer an AGE, or what’s known as an arterial gas embolism. This can prove to be fatal within moments.

If you start experiencing these symptoms after a dive, get yourself to a doctor immediately. Don’t wait!

  • Dry cough
  • Short breath
  • Burning pain in the chest

Neurological Decompression Sickness

Even though what causes decompression sickness often affects the body, it can also sometimes affect the brain. Neurological DCS happens when the nitrogen bubbles start traveling through the diver’s bloodstream and into the diver’s brain. There are many neurological symptoms as well as physical symptoms, and these can all cause serious, permanent damage to the body. If you or someone you know has some of the symptoms below, please immediately take them to a hospital.

  • Blurry vision
  • Passing out or losing consciousness
  • Headaches
  • Moodswings that are unexplained
  • Memory loss
  • Incontinence
  • Paralysis
  • Numbness

Because of just how serious DCS can be, all divers are taught to make a dive plan before heading out to the water. This dive plan must be followed so that the diver(s) can minimize their risk of getting decompression sickness. However, even if the plans are followed, sometimes a diver can still come down with a case of the bends. This usually happens when the diver has some health problems they were previously unaware of.

How Do You Treat Decompression Sickness?

We’ve talked about what causes decompression sickness. We have even talked about the different types of it, as well as their symptoms. So now, you know what to look for and when to take yourself to the doctor.

But how exactly do you treat DCS? How do you “fix” this problem?

Well, two things are often done for divers who are suffering from The Bends. The first is oxygen therapy as first aid (for example, a hyperbaric chamber or a breathing tube/mask/hood). Then this is followed by a therapy process called “recompression” – at least for the more severe cases.

During a recompression therapy session, the diver will be treated inside a sealed chamber. This diving chamber is high-pressure to simulate the pressure in the depths of the ocean. The chamber is often referred to as a recompression chamber or a decompression chamber.

When the diver is inside the decompression chamber, hyperbaric oxygen gets administered through the use of some built-in systems for breathing. This is done until the oxygen levels in the diver’s injured tissues and body parts increases and until the swelling has gone down. Simply put, oxygen will be pumped in until the gas bubbles found in the blood vessels and tissues shrink.

The full treatment can last anywhere from 1 hr and 40 mins all the way to 12 hours, depending on the severity of the case. 12 hours of recompression therapy is often done only for those who are suffering from some really severe symptoms.

What to Do if You Feel Symptoms

Now, if you think that you’re suffering or beginning to come down with a case of the bends, here’s what you need to do.

  1. Stop your dive
  2. Calm down, and do your best to avoid overexerting yourself
  3. Pure oxygen therapy for first aid
  4. Administer first aid if the diver loses consciousness
  5. Call for an ambulance or emergency medical personnel
  6. Drink lots and lots of fluids
  7. List any symptoms or unusual conditions for your medical professional
  8. Give this list to your medical help when they arrive

Are There Any Long Term Effects?

We’re sure that you’re wondering whether there can be permanent effects from decompression sickness. And we’re also sure that you’re wondering what sort of permanent damage you can get from this condition. So let’s answer that question.

If you or a diver you know are suffering from decompression sickness that gets left untreated, especially for a long time, you might be in trouble. You run the risk of your DCS developing from the milder version into one of the more severe versions. And then things can get really serious. You don’t want that – take yourself to a doctor right away.

Other long-term effects include bowel and urinary incontinence, nervous system damage, chronic joint pain, and muscle weakness.

As we said, it can be so bad that your day-to-day quality of life can suffer… and you may find yourself unable to go on any future dives.


FAQ about Decompression Sickness

Why does decompression sickness occur?

Decompression sickness (DCS) is decompression illness or injuries, known simply as “the bends,” is caused by dissolved gases coming out of solution too quickly when the body ascends. The nitrogen and other gases usually come out of solution in pockets within tissues, forming bubbles that can travel to nerves, joints, and other vital organs. DCS commonly affects scuba divers because they are frequently subjected to pressure changes that occur during descent and ascent. Barotrauma frequently occurs during ascent due to over-rapid airway closure, blood vessel injury leading to cerebral stroke, pulmonary obstruction causing closing lung syndrome, or pneumothorax with the collapse of the lung’s interior surface against the chest wall.


At what depth do you get decompression sickness?

Depends on the pressure change. It is possible to get it at as low as 100 ft underwater, and divers are closely monitored with depth gauges and time limits. If you go below 300 feet, the symptoms can become serious. When a diver returns to the water’s surface they usually get better within minutes of coming up and out of that depth zone!


Will the bends go away on their own?

The bends are a pressure-related issue, so it doesn’t really go away on its own. When pulmonary barotrauma occurs, the incoming air puts an inward strain on the lungs which results in overinflation of the lungs and stretching or rupture of lung tissue. A doctor may prescribe a medicine to reduce the severity of your symptoms in extreme cases. 

Final Thoughts

We’ve talked about all there is to know about DCS, what causes decompression sickness, the symptoms and types of this condition, and what to do if you feel like you’ve come down with it. Frankly, we hope that this article has helped you so that you don’t ever have to deal with this issue. Remember to plan your dives ahead of time and stick to that plan when you get to the water. This will help you to minimize your risk of developing DCS. And finally, don’t simply surface from deep below too quickly. If you’re going a significant depth, make decompression stops on your ascent. Don’t forget to account for these stops when it comes to your air supply! Maybe you can bring a small camera to keep you occupied during your stops.