One of the most frequent inquiries we receive at DAN concerns whether it’s safe to dive while taking a particular medication. The answer is rarely straightforward.
Many divers assume DAN has a repository of data on how various medications are affected by the diving environment. Unfortunately, such data do not exist. Ethical concerns preclude formal research trials that would evaluate the influence of drugs on human divers in an underwater environment. Anecdotal reports of dive accidents are of limited value in determining whether it is safe to dive while taking a particular drug; there are too many physical and physiological factors involved to allow isolation of a single variable.
This is not to say it is impossible to provide sound advice when the question is asked. By considering the medical condition being treated, the physical demands on humans in the diving environment and known facts about a drug from clinical trials conducted on land, recommendations can be made about the suitability of diving on medication.
When divers ask DAN about using medications while diving, they are often most concerned about the likelihood of new side effects occurring at depth. It is theoretically possible that certain drugs might potentiate (enhance) or be potentiated by the narcotic effect of nitrogen. This possibility should be considered if a diver plans to dive deeper than 24 metres while taking a drug that warns against drinking alcohol or operating heavy machinery. Aside from this theoretical concern, most drugs are not suspected to incur specific biological hazards due to immersion, pressure or breathing gas mixture. It is understandable for divers to be apprehensive about new side effects occurring during a dive, but the more important issue to medical professionals is whether the underlying medical condition might make diving less safe. The injury or illness being treated is much more likely to exclude someone from diving than the medication.
Diminished physical fitness is not uncommon among people who are being treated for medical conditions. Although diving itself is a relaxing activity for most recreational divers, lifting and wearing heavy equipment as well as entering and exiting the water can be strenuous. Divers should always have sufficient physical capability to fight a current, perform a long surface swim or help a buddy in the event of an emergency. They should not be at increased risk of barotrauma due to congestion, and they should not have symptoms like numbness, tingling or pain that might be confused with decompression sickness (DCS) after a dive.
In addition to the implications of the underlying condition, it is important to consider whether a diver has experienced any side effects from a medication, how long he or she has been taking it, and what other drugs are taken. Before diving with a particular drug, a diver should have experience taking it on land. For most prescription medications, 30 days is recommended in order to ensure the dosage is correct and reveal any side effects the diver is likely to experience. At least one doctor should be aware of all medications an individual is taking to minimise the risk of drug interactions. A diver should not dive if he experiences any side effects that could cause distraction or decreased awareness if they occur underwater.
In addition to these general considerations, there are some specific questions and points for discussion relevant to particular types of medications. The following are questions that should be addressed during the physician’s evaluation of the diver as well as in the diver’s self-assessment.
Orthopaedic Pain Medications and Muscle Relaxants
- Could pain or impaired mobility cause distraction or physical limitation during a dive?
- Might heavy dive gear exacerbate an injury?
- Could side effects of prescription-strength pain relievers diminish a diver’s alertness or awareness?
- Might soreness, numbness or tingling be confused with decompression sickness after a dive?
- Are the diver’s physical capabilities diminished?
- Has the diver ever experienced a seizure?
- Could any drugs the diver is taking cause side effects that might be confused with DCS?
- Might symptoms or drug side effects impair judgment, behaviour, awareness or ability to handle stress?
- Is the patient’s condition managed successfully or in remission?
- Is the patient at risk for gas trapping that could cause barotrauma on ascent?
- Is the diver dehydrated due to vomiting or diarrhoea?
- Does the patient have the cardiovascular health and exercise capacity to safely dive?
- Is a stress electrocardiogram (EKG) needed to confirm good cardiac fitness?
Respiratory Medications Including Inhaled Corticosteroids
- Is there any reason to suspect air trapping or impaired ability to breathe while diving?
- People with asthma should undergo an exercise challenge test. This consists of pulmonary function testing before and after exercise.
Decongestants, Antihistamines and Intranasal Steroids
- Is the diver congested (and therefore at increased risk of barotrauma)?
- Has he or she been congested recently?
- Consider the possibility of the medication wearing off at depth.
- Consider the potential sedative effect of antihistamines.
Hormones, Insulin and Medications Used to Treat Diabetes
- Are the patient’s hormone levels stable and close to normal?
- Is the diabetic diver at risk for hypoglycaemia with exercise?
- Divers with diabetes must have good health and fitness and experience managing blood glucose level while exercising.
- Does this patient have an illness or infection that might be complicated by diving?
- Is the person physically fit to dive?
- Lung cancer warrants particular consideration.
- Med ports are generally not a problem, but should be padded well.
These points should be considered in the context of both the symptoms of the medical condition and the side effects of any drugs used to treat it. The focus should be on whether any of these factors might lead to impairment of a diver’s physical capabilities, awareness, reaction time or judgment. This list is by no means exhaustive, but it highlights some of the concerns that accompany certain medical conditions and the drugs used to treat them. Any medical condition or medication should prompt a diver to seek a physician’s approval prior to diving. As always, DAN is available to discuss the relevant concerns of injuries, illnesses and the medications used to treat them. If you have any questions, contact DAN via email or call +61-3 9886 9166.
By DAN’s Brian Harper, EMT, DMT
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