Beta-blockers are a group of medications that are very versatile and are used to treat a number of conditions. The most common uses of beta-blockers are for the treatment of high blood pressure, abnormal heart rhythm, heart failure, the prevention of heart attacks after a heart attack has occurred, angina, tremors, pheochromocytoma (a type of tumor on the adrenal glands), migraines, hyperthyroidism, anxiety, akathisia (restlessness), and glaucoma. This is a long list and that means that prescriptions for beta-blockers are quite common and are an area of concern for divers.
There are a number of medications in this family including Propanolol/Inderol, Carvedilol/Coreg, Pindolol/Visken, Atenolol/Tenormin, Carteolol/Cartrol, Acebutolol/Sectral, Betazolol/Kerlone, Penbutolol/Levatol, Bisoprolol/Ziac or Zebeta, Labetalol/Normodyne or Trandate, Metoprolol/Lopressor, Nadolol/Corgard or Corzide, Timolol/Blocadren or Timolide. As with any medications a diver may be taking, the side effects of the beta blockers must be considered and there are a number of them that could cause problems while diving.
A major side effect of beta-blockers is drowsiness which can make it difficult for a diver to function properly while underwater. Beta-blockers are often accompanied with a warning label stating that the patient should not drive or operate heavy machinery while taking the prescribed medication. Diving while taking beta-blockers can pose a great risk as a diver must be alert at all times while underwater so that he or she can check gauges regularly and respond to situations and emergencies should they arise. Dizziness is also a potential side effect of beta-blockers as are low blood pressure, decreased pulse rate, and trouble breathing. These side effects may make it difficult for a diver to perform the necessary exercise load required to scuba dive. Individuals may also experience dry mouth, so drinking lots of water is a must to avoid dehydration especially since diving often requires the breathing of cold, dry air. It is also important to note that people who also suffer from asthma or diabetes may have different and special side effects when taking beta-blockers so extra caution is advised in these cases.
Another potential side effect of beta-blockers and one that doctors warn divers about is the potential that the heart will not be able to respond to exercise, resulting in a reduced exercise tolerance. While many might believe that this isn't an issue when it comes to diving because diving is a low energy sport, this is simply not the case. It is true that often times diving is easy and even effortless, but low exercise tolerance can be a major problem if the diver has to fight a strong current or respond to an emergency situation, such as getting caught in fishing net or becoming injured by an animal. Essentially, a diver must be fit to dive and that means being able to withstand a heavy exercise load when the situation warrants it.
If you suffer from anxiety, high blood pressure, heart problems, migraines, hyperthyroidism, or any of the other conditions that are commonly treated with beta-blockers, then you will need to treat the condition before you can safely dive. If you are taking beta-blockers, then it is important for your safety and the safety of others that you are aware of the side effects and how these medications affect you. Every person should be considered on a case-by-case basis as each person responds to medications differently. If you have mild or no side effects, then you should be able to dive safely. If you are unsure of whether or not you should dive, then the best thing to do is to consult with your regular physician or a dive doctor to determine if you are indeed safe to dive. After all, being at risk when on dry land is one thing, but being at risk underwater and in a remote location, where some of the best diving is available, can be a recipe for disaster. Be informed, dive safely, and enjoy!