After diving, I often get minor to severe headaches. What's causing this? There are many different types of headaches, and you'll need to visit a doctor familiar with diving for a thorough examination to determine whether yours are related to diving. Most diving headaches are caused by either carbon dioxide retention or sinus barotrauma. Here are the most common headaches resulting from diving and what you can do to prevent them. Carbon Dioxide Headaches Symptoms: Post-dive localized throbbing pain The carbon dioxide headache, one of the most common for divers, is caused by an increase in the body's carbon dioxide level, which stimulates receptors in the brain's blood vessels. An increase in the brain's blood flow to these receptors leads to headaches. Typically, they are caused by a diver taking shallow sips of air, which allows carbon dioxide to accumulate. This buildup can also occur when a diver "skip breathes" by pausing after each inhalation and holding the throat closed. Taking measured, slow, complete breaths under water is the best way to avoid carbon dioxide headaches, which don't respond to analgesics or migraine medications. Tension Headaches Symptoms: Post-dive neck and head pain New divers often experience tension headaches resulting from the stress of their first experiences in the underwater world. Clenched jaws and muscular stress in the neck and back of the head lead to these types of headaches, which usually disappear once the diver gains experience and becomes more relaxed under water. Migraine Headaches Symptoms: Severe headaches with nausea Post-dive vomiting can be caused by a migraine headache, but, if coupled with other symptoms, could indicate a DCS headache. If the diver has a history of migraine headaches, then there could be a direct correlation between diving and the onset of the cranial pressure. Unless they are able to take measures to prevent a migraine attack, people with migraines should not dive. If the diver has migraines accompanied by visual anomalies, he should be checked for patent foramen ovale, which may be a factor in undeserved DCS hits. DCS Headaches Symptoms: Post-dive headache with neurological deficit A headache that comes on strong after a dive, coupled with other symptoms like nausea, vomiting, joint pain, dizziness, ringing in the ears, muscle aches, localized swelling, itching or skin rash, could indicate the onset of Type II decompression illness or an arterial gas embolism. This, the most severe dive-related headache, requires a quick response from onboard personnel and a call to the Divers Alert Network to coordinate hyperbaric treatment. Sinus Headaches Symptoms: Forehead, face and eye pain during ascent or descent A diver without a history of migraines could be suffering from a sinus headache, especially if he has a history of problems equalizing. Shifting pressure based on changes in depth without proper equalization can lead to sinus barotrauma. This pain usually spreads across the forehead and eyes. Thus, inflammation of the sinuses, caused by colds or allergies, can further complicate diving. Post-dive Fatigue Why am I always tired after diving? My divemaster mentioned something called post-dive fatigue? Fatigue in divers often accompanies more acute signs and symptoms of decompression sickness. For other divers, fatigue is the only complaint. Some experts consider post-dive fatigue to be a subclinical form of DCS, possibly caused by tiny bubbles that form in the veins and then filtered out by the lungs. Fatigue lessens when divers are recompressed, indicating that it may be caused by gas bubbles. On the other hand, anyone who spends the better part of a day out in the tropical sun and breathing compressed air under water is likely to get worn out. If you don't usually lead a fit, active lifestyle, you may just be tired.