Over-the-Counter Medications and Diver Precaution

As divers, we’re taught the perils of alcohol and diving and that drinking and diving don't mix.

What about other drugs — specifically the over-the-counter (OTC) variety — and diving? Is the line so clear-cut about OTC medications that are designated by the U.S. Food and Drug Administration as safe for the short-term treatment of ailments? With literally hundreds of products available to consumers, the choice of the best agent is often difficult. The active ingredient available in a manufacturer's product may also be in many other preparations.

To add to the confusion, many products combine two or more agents to relieve multiple symptoms, as we often see in cold and allergy products.

Dive medical questions abound about OTC medications and their compatibility with safe diving. While such medicines are readily available, that doesn’t mean they are completely safe, whether you're topside or underwater.

OTC Medications Underwater

What happens when you use OTC medications while diving and are subjected to the pressures of depth? There has been little research and thus little documented empirical evidence on the effects of drugs used in a hyperbaric setting. Diving while using most medications is, at best, a matter for you, your doctor and, if necessary, DAN® to discuss before you dive.

About 60 percent of the medications purchased in the United States are nonprescription, OTC products. Self-care and self-medication are popular trends, but what about the appropriateness of using such OTC medications while diving?

These drugs, based solely on their labeling definitions, are considered safe for consumer use; used as directed, they pose a minimal risk and a greater margin of safety than prescription drugs. They are typically used to treat illnesses that can be easily recognized by the user; this contrasts to conditions treated by prescription drugs, which are generally more difficult to assess. The nearly 300,000 OTC drugs on the market far outnumber the 65,000 prescription drugs.

The most commonly encountered OTCs — and probably of greatest concern for the sport or recreational diver — fall in four categories:
• antihistamines
• anti-inflammatory agents
• analgesics
• anti-motion sickness preparations

Forethought

Consider the use of any medication and any underlying need to take it. Does the underlying condition disqualify someone from diving, or does it compromise one’s general safety and that of other divers?

The diver who requires decongestants to equalize his ears and sinuses has an increased risk of serious injury from barotrauma. A seasick diver, medicated or not, may experience in-water disorientation, vomiting, loss of buoyancy control and embolism as a result of breath-holding or violent diaphragmatic movement.

No drug is completely safe, whatever the setting in which it is taken. A drug’s chemical contents, by design, alter body functions through their therapeutic action. They all may have undesirable effects that vary by individual or setting, with sometimes unpredictable results.

In researching your medications, review and familiarize yourself with the active ingredients, warnings and directions from the manufacturer. Learn more from the following information.

Antihistamines

Most often used to provide symptomatic relief of allergies, colds and motion sickness are antihistamines with the active ingredients diphenhydramine hydrochloride, triprolidine hydrolochloride and chlorpheniramine maleate. The word "antihistamine" literally denotes a drug with characteristics that are antagonistic to the actions of histamine and block its affects.

Antihistamines counteract the symptoms of allergies, colds and motion sickness, but they may have side effects. In therapeutic doses, these side effects may include dryness of the mouth, nose and throat, visual disturbances, increased heart rate, drowsiness or an undesired sedation or depression, blurred vision and urinary retention; together or separately, they can affect a diver’s safety. Antihistamines can also depress the central nervous system (CNS), impairing a diver's ability to think clearly and react appropriately when the need arises.

Drowsiness, one of the more troublesome side effects to divers, occurs because of the drug's effect on the brain. Additionally, drowsiness can be heightened by nitrogen narcosis, putting a diver at greater risk.

Since antihistamines reduce secretions (tearing, runny nose), dry mouth can be another bothersome side effect, especially worsened by breathing cold dry air through a regulator. Making sure you are adequately hydrated during the dive trip can lessen this effect. Sucking on hard candy between dives can increase salivation and provide some temporary relief, and saline mist sprays can alleviate nasal dryness.

Decongestants

These vasoconstricting drugs cause narrowing of the blood vessels, which often temporarily improves the nasal airways. Common active ingredients include pseudoephedrine hydrochloride and phenylpropanolamine hydrochloride. Decongestants can cause a mild CNS stimulation and can lead to numerous side effects such as nervousness, excitability, restlessness, dizziness, weakness and a forceful or rapid heartbeat.

Medications known to stimulate the CNS may have a significant and perhaps an undesirable effect on the diver. Additional precautions or warnings may advise against use by those suffering from diabetes, asthma or cardiovascular disease.

Anti-Inflammatories and Analgesics

Consider the underlying condition for taking anti-inflammatory or analgesic drugs. Generally taken for the temporary relief of minor aches and pains, they may provide temporary relief, but the injury itself is still present. Limitations in range of movement because of the injury, swelling or pain can place a diver at risk of additional injury. Such medications may mask mild pain due to decompression sickness; this may result in a subsequent delay in seeking treatment.

Active ingredients include naproxen sodium and ibuprofen, with notable side effects such as heartburn, nausea, abdominal pain, headache, dizziness and drowsiness. Standard precautions discourage their use by those with medical disorders involving heartburn, gastric ulcers, bleeding problems or asthma.

With anti-inflammatories or analgesics, perhaps one of the most significant considerations is potential adverse drug interactions in individuals treated with anticoagulants, insulin and nonsteroidal anti-inflammatory drugs (NSAIDs).

Anti-Motion Sickness Preparations

It's best not to self-medicate here; specific warnings regularly prohibit the use of these medications without consulting a physician. It's generally agreed that — at any time — recreational divers should use these medications with caution.

As with some antihistamines, these medications may typically contain meclizine hydrochloride, dimenhydrinate, diphenhydramine hydrochloride and cyclizine. Common side effects are drowsiness and fatigue. Coupled with impairment of a diver's ability to perform hazardous activities requiring mental alertness or physical coordination, these side effects will definitely not enhance the pleasure of a dive.

Underwater Pressures

Any medication that affects the CNS, such as antihistamines, decongestants and anti-motion sickness medications, can interact with increased partial pressures of nitrogen. How? Although there is no scientific data, it is reasonably suspected that the sedative effects of antihistamines and motion sickness medications may be exaggerated by nitrogen narcosis. They may even lower a diver’s resistance to narcosis. In addition, nitrogen may have a synergistic effect, enhancing the sedative or stimulant quality of the drug.

Furthermore, because of the increased intensity of these effects, a new and unexpected reaction such as panic may occur in an otherwise rational diver. These side effects will vary from diver to diver and from day to day for the same diver. No one can predict who will have a reaction while diving.

Can I Dive?

What does this mean for the recreational scuba diver? Many doctors knowledgeable in dive medicine will quickly advise anyone who requires medication to dive to wait out the illness. Heed the following:
• Consult your physician when you are ill; your doctor may be able to provide you with a more effective medication and counsel you on your fitness to dive.
• Study all the information supplied with your medication and understand the warnings, precautions and the effects it may have on your body.
• Try the medication at least one or two days before diving; this may help you assess your reaction to the drug.

The decision to dive is personal and one of acceptable risk. The choice of acceptable risk is a matter of judgment, with careful attention given to the risk versus the benefits and one’s ability and willingness to deal with possible negative consequences.