Can you dive with a cold?
You should not dive if you have a cold, congestion, or sinus blockage. Equalizing your ears and sinuses depends on open air passages, and a cold can block them. If you try to dive while congested, you may be unable to equalize properly, leading to painful pressure or even ear or sinus barotrauma. Some divers feel fine at the surface but find they cannot equalize after descending only a few feet, which can end a dive immediately.
You will see hundreds, if not thousands, of divers online saying they take cold medicine before every dive to make equalizing easier. To me, that is a bad risk calculation, and I do risk calculations for a living. Decongestants can wear off underwater, trapping air in your sinuses during ascent and causing injury. They can also raise your heart rate or make you feel lightheaded. If you cannot breathe clearly through both sides of your nose, skip the dive. It is not worth the risk.
I have canceled dives because of congestion, and while it is disappointing, it is far better than injuring yourself and sitting out for weeks. There will always be another dive.
Medical Risks
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Equalization Techniques for Scuba Divers
Most effective techniques for equalizing ear pressure during descent, including Valsalva, Toynbee, and Frenzel. Clear your ears comfortably and safely.
How to Avoid Getting Sick on a Dive Trip
Stay healthy on your scuba trip with tips to avoid dehydration, food poisoning, motion sickness, sunburn, jet lag, and minor injuries while diving abroad.