Hiking on Drugs

2022, November/December Adirondac

No, not those drugs …
Hypertension (high blood pressure), a major cause of cardiovascular death affects over 100 million Americans, 80 percent of whom are on medication for the problem. As I have discussed in other columns, aerobic exercise such as wilderness travel has a major positive impact on hypertension. This observation is tempered by the fact that several of the common medications used for hypertension may affect the hiker negatively. Although this is not a reason to avoid wilderness pursuits, being aware of the effects of several types of antihypertensives can help one prepare to enjoy a trek without nasty complications.

There are literally hundreds of individual antihypertensive drugs. I will focus on four categories that include the vast bulk of prescription medicines for hypertension and have specific concerns for backcountry use. I will avoid using names of the individual drugs since there are so many of them. Readers should check with their pharmacist or provider (or, of course, Google) to learn into which categories their own prescriptions fall.

The group of drugs that may be the most problematic are the beta blockers. These drugs lower blood pressure by interfering with the strength and rate with which the heart beats. They are highly effective medications, and particularly beneficial for those with prior heart attacks.

Most individuals experience fatigue and lowered exercise capacity when beginning beta blockers, although these effects may lessen with time. For some, however, beta blockers make strenuous exercise such as climbing a peak nearly impossible. Hiking requires an increase in the rate and strength of the heart’s contractions; this increase may be severely limited by beta blockers. Regardless of one’s prior experience, it would be unwise to plan a major hiking trip after starting a beta blocker without having a good idea of one’s current exercise capacity This would best be assessed by a series of hikes of gradually increasing length and difficulty.

There are a number of specific beta blockers, which vary in their impact on exercise capacity. This would be an important discussion with one’s provider before beginning the drug.

Diuretics are a group of drugs that increase urine output, lowering blood pressure by reducing blood volume. After being on a diuretic for a while most patients reach a new equilibrium of fluid balance and are generally comfortable.

Trekking, however, can upset this equilibrium by increasing the need for fluids. Thus, there may be a greater risk of dehydration for hikers taking diuretics. This may show itself with fatigue, light-headedness, and excessive thirst. Hikers experiencing such symptoms while taking diuretic, should increase their intake of fluids such as water, as well as salty snacks. As with many such things, there is no real “rule” for doing this, besides carefully heeding the signals of one’s own body.

Angiotensin converting enzyme inhibitors (ACE inhibitors) and angiotensin receptor blockers (ARBs) are two different categories of antihypertensive that have similar mechanisms of action. These drugs inhibit a hormone that typically constricts blood vessels, thus lowering blood pressure. This effect may interfere with the body’s usual ability to raise blood pressure upon standing or becoming slightly dehydrated. Patients may therefore experience dizziness or lightheadedness when getting to a standing position or upon arising in the morning. While annoying, this is seldom dangerous. It is wise to be careful moving to stand, such as after stopping on the trail for a rest. One should also avoid dehydration while on these drugs.

Calcium channel blockers relax the tension in blood vessels, lowering blood pressure. Like ACE inhibitors and ARBs, these drugs may render one lightheaded upon standing, especially if slightly dehydrated.

~Tom Welch, MD, is a physician at Upstate Medical University in Syracuse and an active member of the Wilderness Medical Society. He is a licensed professional guide and a certifying instructor for the Wilderness Education Association, and has guided groups in the Adirondacks, Montana, and Alaska. More information is available at his website and blog, adirondoc.com.

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Topics: Diet & Nutrition, Drugs, General First Aid