Scuba diving is a relaxing activity, but of course you should be in good health. You will realize that there are times when strenuous activity comes into play, so you need to levels of health, fitness and conditioning sufficient to handle strenuous activity, which could include an emergency or other unanticipated physical demands. Being in good health helps insure that you can meet these demands, which in turn affects your safety.
General diving health recommendations follow the same recommendations regarding rest and diet for everyday life. Never use alcohol, drugs or tobacco prior to diving. Alcohol and drugs, even in quantities that have minimal effect on the surface, can impair your judgment at depth, where pressure can increase your risk of decompression sickness. Be conservative if drinking the night before diving; alcohol tends to dehydrate you, which can also predispose you to decompression sickness.
If you are taking prescription drug, discuss its effect with your physician prior to diving. If in doubt, do not dive until you're no longer using the medication.
Avoid smoking which interferes with having an active lifestyle. Smoking is undeniable detrimental to your health. If you do smoke, abstain for several hours before and after diving because smoking significantly decrees the efficiency of your circulatory and respiratory systems. It also can promote air trapping within your lungs, theoretically raising your risk of lung over expansion injury – even when breathing normal.
Do not dive if you do not feel well, including diving with a cold. Doing so can cause ear and sinus squeeze or reverse blocks due to equalization difficulties. Diving with a chest cold can produce air trapping, with a risk of lung over expansion injury. No one wants to miss out on a dive, but you should be in good health to go safely. Do not use medication to combat the symptoms so you can make a dive if you are not well.
Maintain a reasonable degree of physical fitness and have a complete physical examination when you first enter diving, and at least every two years thereafter. Ideally, you should be examined by a physician knowledgeable in dive medicine. Keep your immunizations current; This is especially important for your tetanus and typhoid immunization. Keep a well-balanced diet and get proper rest. Maintain a regular exercise program – you do not have to be an Olympian, just in good average health.