Diving and Your Health: Colds, Blood Pressure, Medication, Seasickness and More

Colds, flu and congestion

Don't dive with a cold, flu, hay fever flare-up or sinus infection. Congestion makes equalizing difficult and raises the risk of ear and sinus barotrauma, including painful "reverse block" on ascent. Coughing and phlegm can also make regulator breathing unpleasant. Wait until you're fully recovered and can equalize easily on land. Missing a dive is always better than missing a week of diving with a damaged ear.

Blood pressure

Well-controlled high blood pressure is often compatible with diving after medical assessment. Uncontrolled high blood pressure is not. Some blood pressure medications, such as certain beta-blockers, can affect exercise capacity or airway responsiveness. A doctor needs to evaluate your overall heart health and medication, especially if you're older or have other risk factors.

Medications

The key questions are: what is the medication treating, and could its side effects be dangerous underwater?

• Drugs that cause drowsiness (some antihistamines, sleeping tablets, strong painkillers, some anti-nausea tablets) can combine with nitrogen narcosis and impair judgement.
• Anticoagulants (blood thinners) may increase bleeding risk from barotrauma.
• Drugs for conditions such as epilepsy, heart disease, diabetes or mental health need specialist review.
• Try any new medication on land first, well before a dive trip, to learn how it affects you.

Seasickness

Seasickness is common on dive boats and can be miserable, and vomiting through a regulator underwater is unpleasant, although it can be done. Tips:

• Choose a large, stable boat or shore diving if you're prone to it
• Stay on deck in fresh air, look at the horizon, and stay near the middle of the boat
• Eat a light, bland breakfast; avoid greasy food and alcohol the night before
• Get ready quickly and get in the water. Most people feel better once submerged
• Ask a doctor or pharmacist about non-drowsy options and try them on land first

Ginger, acupressure bands and staying hydrated help some people.

Hydration and heat

Breathing dry tank air, sweating in a wetsuit under the sun, and sometimes being seasick all dehydrate you. Dehydration may increase decompression stress. Drink water regularly throughout the dive day. Your urine should be pale. Limit coffee and alcohol.

Sun and skin

Dive days mean hours on boats. Use a hat, sunglasses and a rash guard, and choose reef-safe sunscreen (mineral-based zinc oxide or titanium dioxide, free from oxybenzone and octinoxate). Some destinations ban chemical sunscreens. Remember that sunburn under a wetsuit is very uncomfortable.

Periods, contraception and pregnancy

• Menstruation: there's no evidence that diving during your period attracts sharks or is unsafe. Use whatever protection you're comfortable with. Some women feel more fatigue or cramps, and staying warm and hydrated helps.
• Contraception: the pill is generally considered fine for diving, but discuss any clotting risk factors with your doctor.
• Pregnancy: diving is not recommended at any stage of pregnancy, and many divers avoid it when trying to conceive.

Injuries and recovery

Cuts and scrapes should be cleaned and kept covered. Open wounds heal slowly in seawater and can get infected. After surgery, broken bones or significant injuries, get medical clearance before diving. Recent dental work can also cause "tooth squeeze" if air is trapped under a filling.

Smoking and vaping

Smoking damages lung function, increases carbon monoxide in the blood and raises heart risk. It's a strong reason to quit. At minimum, avoid smoking or vaping for several hours before and after dives.

Recognising decompression sickness

Symptoms usually appear within minutes to hours after a dive (most within 6 hours, occasionally up to 24–48 hours). Watch for:

• Unusual fatigue, joint or limb pain
• Numbness, tingling, weakness
• Skin rash or mottling, itching
• Dizziness, confusion, headache, difficulty breathing

If you suspect DCS: stop diving, lie the diver down, give 100% oxygen if trained, keep them hydrated if conscious, and contact emergency services and your dive insurance / DAN hotline. Early treatment in a hyperbaric chamber matters. Don't "wait and see".

Frequently asked questions

Can I dive after drinking alcohol?

No. Alcohol impairs judgement, dehydrates you and may increase decompression risk. Avoid it before diving and keep it moderate afterwards. See our guide to sleep, food and alcohol.

Can I dive with high blood pressure?

Possibly, if it's well controlled and a doctor clears you after checking your overall heart health and medication. Uncontrolled high blood pressure is a reason not to dive.

What seasickness medicine is safe for diving?

Some anti-seasickness medicines cause drowsiness, which is risky underwater. Ask a doctor or pharmacist about non-drowsy options and test them on land before a dive day.