In the 19th century, doctors had few cures and lacked a basic understanding of biology to be able to treat most illnesses. They continued to rely on traditional remedies, such as bleeding, purging and vomiting, to relieve the patient's symptoms.
Into that void came patent medicine. Not actually patented - their ingredients were kept secret - these medicines were hawked at traveling medicine shows and through newspaper and magazine advertising. Like Dr. Caldwell's Syrup Pepsin, they claimed to cure many ills. Because approximately 80% of illnesses cure themselves, these medicines could boast a high success rate.
Patent medicines consisted of alcohol, opium or some narcotic derivative. Given these ingredients, they could offer people temporary relief from what ailed them, but did not cure disease. The dangers of patent medicines led Congress to pass the Pure Food and Drug Act in 1906, to ensure that drugs had accurate labeling, but manufacturers did not have to have safety trials until 1938 or prove the effectiveness of drugs until 1962.
With the introduction of sulfa drugs in the 1930s and penicillin and streptomycin in the 1940s, the medical establishment pushed alternative medicine to the side. More recently, growing concerns about the limits, costs and other drawbacks of modern medicine and the apparent effectiveness of alternate treatments such as acupuncture, herbs and chiropractic in many cases has led to greater public acceptance of these approaches to disease.