Modern medicine includes thousands of medications to bring relief from illnesses. Which of these are safe to use while diving? Are there hazards associated with the use of non-prescription drugs? What happens when pressure and medication are combined? Are social drugs hazardous in the diving environment? See if your concepts on this topic agree with the findings of diving physicians and various studies on the subject. Note: Select all correct answers. Some questions have more than one correct response.

1. The effect of pressure on drugs taken by divers will cause:

A. The effect of the drug to be intensified
B. The effect of the drug to be reversed
C. Unforeseen effects to occur
D. No change in the effect of the drug

2. As long as a decongestant can be tolerated above water with no adverse effects, it can be used without problems when diving.

A. True, provided the medication is non-prescription
B. True, as long as the recommended dose is not exceeded
C. False, because the medication may lose effect underwater
D. False, because decongestants predispose to seizures underwater

3. Which of the following statements regarding alcohol is true?

A. A person who drinks – before or after diving – is more likely to get decompression sickness than one who abstains
B. A person who drinks before diving is more likely to become chilled than a person who abstains
C. A person who drinks is less susceptible to narcosis than one who abstains
D. A person who drinks before diving is less likely to experience respiratory distress underwater than a person who abstains

4. Which of the following statements regarding diving under the influence of marijuana is false?

A. The effects are radically different in cold water versus warm water
B. Marijuana tends to increase breath-holding ability
C. Marijuana makes divers feel warmer in cold water
D. Overwhelming anxiety and fixation on fears are common symptoms

5. Which of the following, in large quantities, can cause dangerous variations in heart rhythm?

A. Pain relievers
B. Cigarettes
C. Coffee
D. Decongestants
E. Motion sickness medication

6. Generally speaking, antihistamines and decongestants. Therefore, use of should be avoided when diving.

A. Stimulate, sedate, decongestants
B. Sedate, stimulate, decongestants
C. Stimulate, sedate, antihistamines
D. Sedate, stimulate, antihistamines

7. When drugs are used in combination under pressure, the increased pressure tends to:

A. Be completely unpredictable
B. Intensify the effect of each drug
C. Intensify the effect of one drug
D. Nullify the effects of both drugs

8. Select the true statement(s) regarding motion sickness medication.

A. Most prescription medications for motion sickness produce undesirable effects for divers
B. Over-the-counter motion sickness medications are generally acceptable for divers
C. It is better to risk motion sickness than to risk the side effects of medication for the illness

9. Smoking reduces diver performance capabilities by:

A. Reducing the oxygen carrying capability of the blood
B. Increasing the risk of an air expansion injury
C. Reducing breath-holding ability
D. A and B, but not C, are correct

Drugs and Diving

Answers: Drugs and Diving

1. C. Unforeseen events to occur. The effects of drugs under pressure are unpredictable. The effectiveness may be lost completely, or may disappear sooner than expected. Even worse, the effect of the drug may be intensified to the point of being dangerous. For example, it is not uncommon for a diver to lose consciousness U/W from a drug which produces drowsiness above water. Caution, discretion and medical advice are in order.

2. C. False, because the medication may lose its effect underwater. Pressure, perhaps because of increased oxygen partial pressure, causes the effects of some drugs to wear off more quickly than on land. For example, when a decongestant loses its effectiveness underwater, air can be trapped in air spaces and a serious reverse block situation can result during ascent. There is also a phenomenon known as the rebound effect, where congestion is worse when the medication wears off than it was prior to taking the drug.

3. A and B are correct, and perhaps C. Alcohol causes skin vasodilation, which results in more nitrogen being taken up and/or released. This increases susceptibility to decompression sickness. And, bends symptoms might be masked or not distinguished in a diver who has imbibed. The increased circulation to the surface of the body also causes increased heat loss, which is undesirable for divers. Resistance to narcosis usually parallels a person’s tolerance for alcohol, but one should absolutely not be under the influence of alcohol when diving.

4. B and C are false. Breath-hold ability may be reduced by as much as 75 percent under the influence of marijuana. Tolerance to heat loss may be reduced by as much as 90 percent. The effects of marijuana vary greatly with water temperature, but are extremely hazardous. This drug may be socially popular with some divers topside, but should be completely rejected whenever diving is being considered.

5. All of the answers are correct. Normal diving causes some changes in heart rhythm, but dangerous dysrhythmias can be produced when drugs are present. Even seemingly harmless activities, like heavy smoking or the consumption of large quantities of coffee, can contribute to the problem. Decongestants stimulate the heart and predispose to dysrhythmias, as do some pain relievers and any stimulant drug.

6. D. Sedate, stimulate, antihistamines. In the zest to make a dive with a stuffy head, divers resort to a variety of medications to open clogged airways. The sedative effect of some antihistamines can be increased under pressure. Any drug which produces drowsiness should be avoided when diving. Antihistamines can also reduce mucus production, blur vision, and cause rebound congestion. Postponement of diving is probably a better option then use of antihistamines.

7. A. Be completely unpredictable. The interaction of drugs under pressure is complex and unpredictable. The late Dr. Charlie Brown expressed the problem well by stating that drug interactions can defy imagination. He stated further, “A decongestant that raises blood pressure might instead lower it if compazine is aboard. Most interactions are not understood, and testing them in the water is a form of Russian roulette.”

8. A, B, and C are true. Generally speaking, non-prescription medications, such as Marezine and Bonine, are tolerated quite well. Perhaps the best preventive of all is quite natural and harmless. Ginger root capsules – two to three per hour – have proven more effective than any commercial medication for motion sickness.

9. D. A and B, but not C, are correct. Carbon monoxide in cigarette smoke combines with hemoglobin in the blood to reduce oxygenation. Smoking also affects the circulatory system in other undesirable ways. The risk of air expansion injuries in the polluted lungs of smokers is well known. Divers need all the physical resources available, and smoking reduces ability, except for breath-holding (smokers adapt to high levels of carbon dioxide in their system). Divers should not smoke.

Previous articleRiding the rips
Next articleEmergency swimming ascents


Please enter your comment!
Please enter your name here