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What Causes Post-Dive Headaches?

Surfacing with a pounding headache after a dive can really take the enjoyment out of going underwater and may even cause you to miss dives or give up diving altogether. Here, we’ll examine reasons for and prevention of post-dive headaches.

Surfacing with a pounding headache after a dive can really take the enjoyment out of going underwater and may even cause you to miss dives or give up diving altogether. We can trace most post-dive headaches, however, back to several easily preventable causes. Here, we’ll examine reasons for and prevention of post-dive headaches.

Dive long enough and you will surface with a headache at one time or another. According to DAN, headaches are one of the most common complaints of divers who contact the organization. To get to the bottom of the problem, it’s important to look at when post-dive headaches occur to try and find a common cause.

Generally, a one-off headache that goes away spontaneously after a dive, or after taking mild headache medication, is rarely a cause for concern. Repetitive headaches, or those not clearing easily, may require a closer look, however.

Ill-fitting equipment

Ill-fitting equipment can be one of the main culprits when it comes to post-dive headaches. New divers, in particular, often over-tighten their mask strap, hoping it will prevent water from entering the mask. Over the course of a dive, however, the strap can put tension on the face and around the skull, leading to a headache.

Another culprit might be a hood that’s too tight or the neck seal of a drysuit that doesn’t quite fit right. At the same time, a hood that’s too wide is a poor insulator against cold water and may lead to too much of the diver’s face being exposed. A so-called ‘ice cream headache’ is often the consequence.

It’s worth taking the time to try on various masks, hoods, and adjusting neck seals until they fit well. The more comfortable you feel underwater, the more likely you are to dive more, and vice versa.

Another pain point could be your tank valve. Especially if you have previously experienced neck or shoulder problems and feel that your neck is in an unnatural position throughout the dive, this may result in a tension headache. Some divers report this problem when they start diving in trim. Just like holding a yoga position, your body may take a bit of time to get used to the position, so take a few minutes during your dive to relax and stretch to avoid excessive tension.

Sinus problems and squeezes

It’s worth considering where your head hurts. If your headache manifests in the frontal area, behind your forehead, for example, poorly equalized sinuses might be the cause. Equalization may be one of the first skills diving students learn, but not everyone masters it right away.

Divers may also sometimes dive with a slight cold and equalize forcefully or perhaps incompletely, which may lead to a reverse squeeze on ascent. All these scenarios can cause headaches.

Mask squeezes may be another cause. If you are task-loaded on your descent and equalizing your mask is not yet automatic, a mask squeeze will manifest with some trauma around your eyes (in bad cases, you may end up with two black eyes) and with a headache. The easiest prevention is to include equalizing your mask in your descent routine.


Dehydration plays a role in many dive-related problems. Especially when tech diving or diving on consecutive days, it’s crucial for divers to hydrate regularly and prevent dehydration in the first place. That doesn’t mean downing ½-gallon of water first thing in the morning after a big night out, but instead hydrating regularly and limiting alcohol, caffeine, and other diuretics to avoid creating an electrolyte imbalance in the body.

Dehydration has also been linked to decompression sickness, giving divers even more reason to prioritize regular and consistent hydration.


Other sources of post-dive headaches are carbon monoxide and carbon dioxide. Carbon monoxide is most often associated with cylinders filled from unsuitable sources, such as a compressor air intake near a busy road pulling in car exhaust fumes, for example. A badly maintained compressor pumping insufficiently filtered breathing gas may be another reason.

Carbon monoxide headaches tend to be severe and can be accompanied by nausea, dizziness, and vomiting. They often start during the dive and, contrary to minor headaches, they are impossible to ignore. If you suspect someone has a carbon monoxide headache, it’s best to get the diver out of the water and give them oxygen. Depending on the severity,  you may also require professional medical treatment.

Carbon dioxide headaches, on the other hand, are mostly related to improper breathing techniques such as skip-breathing and overexertion. Our bodies produce CO2 when we metabolize oxygen, and it is needed to trigger our breathing reflex. However, too much CO2 starts causing several problems.

Overexertion leads to excessive CO2 build-up and retention in our body. If the diver doesn’t stop to relax, the CO2 excess can lead to strong gas narcosis, thus negatively influencing decision-making underwater. CO2 build-up has also been associated with a higher susceptibility to oxygen toxicity and DCS.

Skip-breathing is another cause of CO2 retention as divers limit the gas exchange taking place in their lungs. By skipping breaths, we minimize both the amount of CO2 that is removed from our bodies and the amount of O2 that is inhaled and distributed from our lungs to the rest of the body. In the short term, skip-breathing may appear to reduce gas consumption, but it’s not worth it considering the consequences of allowing CO2 build-up and retention.

Another factor in CO2 retention is gas density. Associated with taking dense gases, like air, to greater depths, this is especially a concern for technical and rebreather divers.

Some divers report feeling better when diving nitrox. While there appear to be quite a few divers who feel this effect, there is no real scientific evidence of this to the best of the author’s knowledge. Saying that, if diving nitrox fits your dive profile, either by extending bottom time or making your dive more conservative, this should be enough reason to use it.

Stress and Anxiety

How did you feel about the dive? If you enter the water stressed out or anxious about the dive ahead, this is likely to lead to a headache. Stress itself cannot be avoided— maybe this is the check-out dive for your next qualification? Maybe there are certain skills that you must perform on this dive to stay on track? But our response to stress is under our control. Ensuring a thorough briefing, sharing your concerns with your buddies, dive team, or your instructor will all go a long way toward managing the stress or anxiety you feel.


Most diving headaches are not serious and are easily resolved. However, they can be a sign of decompression sickness. If your post-dive headache accompanies a particularly deep or long dive profile or a rapid ascent, or if you surface with any other DCS-related symptoms, it’s time to contact DAN or the nearest hyperbaric chamber for guidance.

If you have serious concerns about your post-dive headaches or if they become anything more than a minor inconvenience, consult a diving physician for professional medical advice. After all, dive trips should be something enjoyable, and post-dive headaches should never ruin the fun.