Ms. W was in her late 20s, but chronic illness had ravaged her body, giving her the appearance of a woman 30 years her senior. As a first-year resident physician, I was caring for her in the intensive care unit during her fourth hospitalization in just a few months. She had life-threatening liver disease and signs of a serious infection, and when she first was admitted, she was tearful and shivering, writhing in pain and clutching her mother's hand. Her body's own defense mechanisms had destroyed her liver, which in turn had seriously hampered her immune system. It unfortunately wasn't surprising, then, that we found numerous infections in her liver and lungs. Once these pockets of fluid were drained, and after she had received antibiotics and pain medicine, she became more comfortable and more stable.

One morning after rounds, I glanced over at Ms. W's room and saw an unfamiliar woman walk in and pull the curtain closed at the room’s entrance. The visitor was a reiki practitioner who had come at Ms. W’s request. In reiki, the practitioner uses his or her hands to transfer so-called vibrational energy to the recipient in an effort to promote healing or increase well-being. It hasn’t been shown to be an effective treatment for any condition, and numerous medical organizations—including the American Cancer Society and the National Center for Complementary and Integrative Health—recommend against reiki as a primary treatment for illnesses such as cancer. My patient was sick frequently enough to be well known to many services at the hospital, including the one that provides reiki to patients who desire it.

I saw Ms. W suffer immensely, enduring more pain during her weeks in the hospital than most would experience in a lifetime. Yet she told me that reiki helped her persevere despite this suffering; she felt relaxed and refreshed after her reiki sessions, she said. I was overjoyed that she'd found some solace and relief in reiki, but found myself wondering how effective practices such as reiki—so-called "alternative" or "complementary" therapies—really are. Of course, the extent to which these remedies have been proven vary as widely as the practices themselves, from yoga and tai chi to acupuncture.

For example, yoga and tai chi have demonstrated real physical benefits. Specifically, yoga has been shown to lessen pain among patients with wear-and-tear arthritis of the knee, and to curb discomfort and decrease the use of pain medicines among people with low back pain. Tai chi is linked to improved balance, mood, and coordination among patients with multiple sclerosis, and to lower levels of inflammation among breast cancer survivors. Practicing tai chi also has been associated with a lower risk of depression. The simplest explanation for the benefits of yoga and tai chi is that these practices essentially constitute exercise. After all, physical activity is a key to health.

Yet not all alternative therapies have proven benefits, and in many cases, high-quality scientific data are sparse. Reiki, for example, is widely considered pseudoscience in the medical and scientific communities. One study found reiki improved mood and quality of life among patients receiving chemotherapy for breast cancer – but so did simply being assigned a companion with whom to spend time. In other words, perhaps it is not reiki’s purported “energy exchange” that is beneficial, but rather the sense of companionship and support stemming from spending time with another person.

Interestingly, some patients who use alternative therapies freely acknowledge that the benefits of such practices may arise simply from the respite or companionship they provide. Ms. H, for example, was a patient of mine who suffered from severe pain as a result of advanced breast cancer. When I asked her why she enjoyed receiving acupuncture, she shrugged, saying she enjoyed the company and found that lying still during the hourlong session provided a refreshing period of rest.

Of course, these therapies have a financial cost, which may be borne by the patient, insurance company, or hospital, depending on the circumstance. It’s also important to keep in mind the sometimes steep opportunity cost of choosing unproven alternative therapies over medical treatment. That’s because time is a key factor in any treatment, “alternative” or otherwise. Luckily, neither reiki nor acupuncture stopped Ms. H and Ms. W from undergoing life-saving medical treatment and didn’t prevent proven treatments from working effectively.

That’s a stark contrast from pursuing solely unproven therapies at the expense of treatments that extend life or improve its quality. On the hospital wards, for example, was a patient who deferred proven treatment for his cancer in favor of receiving injections of a caustic chemical the patient thought was more “natural.” Predictably, these injections did not shrink his cancer. Worst of all, repeat imaging showed that the cancer had become widely metastatic. The patient had lost precious time that would have been crucial to halting the spread of his cancer, and now his prognosis was much worse.

Of course, when it comes to treating patients with painful, life-threatening diseases, the goal of our care should be to lessen suffering, regardless of where such relief originates. A few months after Ms. W left the hospital, I learned that she had died, and the news hit me hard. I thought back to her treatment under our care and hoped that even among the misery, we had eased her suffering through our therapies—“alternative” or not.

Allison Bond is a resident in internal medicine at Massachusetts General Hospital in Boston. Her writing about science and medicine has appeared in a variety of publications, including The New York Times, Scientific American, Scientific American MIND, Discover magazine, and Reuters Health.