In his work Of the Epidemics, the Greek physician Hippocrates encouraged doctors to “have two special objects in view with regard to disease, namely, to do good or to do no harm.” Yet the history of medicine has been an exercise in trial and error, with remedies sometimes proving more dangerous than the disease.

Examples of such dubious and sometimes potentially deadly cures abound in the first edition of The Merck Manual of Diagnosis and Therapy, the oldest continuously published English-language medical textbook. First published by the American drug manufacturer Merck & Co in 1899, the manual’s original edition suggests remedies such as hot baths for heat exhaustion, coffee for insomnia, nitroglycerin for headaches, and opium for constipation.

“What’s most fascinating to me are drugs that have an immediate dangerous effect,” says Robert S. Porter, M.D., editor-in-chief of the manual’s 20th edition, which was published earlier this year. “Cocaine for angina? Cocaine is a vasoconstrictor that causes heart attack. Give it to someone with angina and they might die. The bulk of the book is things that simply don't work—that are useless or odd—but these ones really raise questions as to how people could recommend them.”

Here's a selection of puzzling remedies from the first edition, some of which went on to be recommended for decades.

1. ARSENIC FOR ANEMIA

Merck's 1899 Manual of the Materia Medica, Internet Archive // Public Domain

Arsenic was one of the top remedies the manual recommended for anemia. Though arsenic had been known as a poison since ancient times, medicines containing small doses of the substance were long used for conditions ranging from anthrax to syphilis to anemia. By the 19th century, arsenic was being inhaled as vapors, ingested, injected, and given in enemas for a variety of ailments. In fact, so many people suffered symptoms—such as rashes, stomach distress, and headaches—from taking arsenic remedies during the Victorian era that their ailments are now sometimes referred to as “Fowler’s disease," after the popular remedy Fowler’s Solution, which contained potassium arsenite.

2. LAXATIVES FOR CHICKENPOX

Merck's 1899 Manual of the Materia Medica, Internet Archive // Public Domain

Before chickenpox vaccinations became available in the U.S. in 1995, an average of 4 million people each year suffered through itchy outbreaks. When the Merck Manual was first published, part of the comprehensive treatment plan for an "eruptive fever"—whether it was chickenpox, smallpox, or scarlet fever—was laxatives, ideally a dose of castor oil. The idea was to purge the body of the infectious disease, but such treatment usually just compounded the misery and forced the patient to stay close to the toilet.

3. STRYCHNINE FOR CONSTIPATION

Merck's 1899 Manual of the Materia Medica, Internet Archive // Public Domain

Even a tiny dose of strychnine can cause convulsions. Yet the Merck Manual, following the medical practice of the day, recommended small amounts as a treatment for acute constipation. Commonly derived from the plant Strychnos nux-vomica, strychnine was thought to improve gastric function. (Strychnine injections were also recommended for both flatulence and ulcers.) Opium and turpentine were also recommended, but patients probably derived more relief from the less dramatic manual-recommended regimens, such as eating apples and figs or drinking coffee.

4. CHLOROFORM FOR HICCUPS

Merck's 1899 Manual of the Materia Medica, Internet Archive // Public Domain

Bad case of the hiccups? Today, you might be told to hold your breath or drink water. But in 1899, your doctor might recommend inhaling chloroform. An organic compound that also a popular anesthetic in the 19th and early 20th century, chloroform eventually fell out of favor because of its potential to damage the nervous system, liver, and kidneys. Other hiccup remedies listed in the Merck manual included nitroglycerin and the slightly less toxic sugar and vinegar.

5. INHALING SMOKE FOR ASTHMA

Merck's 1899 Manual of the Materia Medica, Internet Archive // Public Domain

As counterintuitive as it seems today, the manual noted that "smoking is sometimes beneficial" for asthma, adding that “cannabis indica can be used in chronic cases.” The manual was far from alone in recommending the practice; throughout the late 19th and early 20th centuries, inhaling the fumes of tobacco and cannabis, as well as stramonium (a hallucination-inducing nightshade) and lobelia (a flowering plant known for its sedative properties) were popular treatments for asthmatics. There were even special anti-asthma cigarettes. We now know that inhaling any kind of smoke has been shown to damage and eventually reduce the number of cilia—the fine lung filaments which, when healthy, help transport mucus in the lungs—which only leads to a worsening of asthma symptoms.

6. BLOODLETTING FOR NAUSEA

Merck's 1899 Manual of the Materia Medica, Internet Archive // Public Domain

Bloodletting—with leeches or other means—has been used to treat various ailments, including excessive bleeding, for thousands of years. The Ancient Greek physicians thought that it was sometimes necessary to balance blood and other bodily fluids, known as humors. The practice remained a standard treatment for many ailments, including nausea and morning sickness during pregnancy, well into the 19th century. It was thought to regulate the pulse, alleviate fever, and calm pain. While bloodletting can actually help with a few conditions, such as hemochromatosis (a genetic disorder leading to abnormal iron accumulation in the liver), doctors eventually realized that bleeding could also weaken patients and that frequent cutting could lead to infections.

As well as this traditional remedy, the manual’s first edition also recommended cocaine, the wonder drug of the day, to treat all kinds of nausea. Better and less stomach-turning effects could have been achieved with another recommended remedy: cinnamon.

7. COLD DOUCHES FOR INSOMNIA

Merck's 1899 Manual of the Materia Medica, Internet Archive // Public Domain

Alcohol, cannabis indica, and “cold douches” were effective remedies for insomnia, according to the Merck Manual. Cold douches—being blasted with cold water—might not seem sleep-inducing, yet in the late 19th and early 20th century this form of hydrotherapy was recommended as a way to improve circulation, fight infection, and treat headaches as well as insomnia. “By this means, the brain is enabled to resume a healthier mode of action, and sleep follows as a matter of course,” wrote Dr. Henry M. Lyman in his 1885 book Insomnia and Other Disorders of Sleep. Other remedies the manual recommended for insomnia included coffee, alcohol, and putting hot water bags on your feet while applying cold ones to your head.

8. BELLADONNA FOR COLIC

Merck's 1899 Manual of the Materia Medica, Internet Archive // Public Domain

Misguided medical notions were also applied to easing colic—the severe bouts of stomach pain often suffered by very young babies. The Merck Manual recommended ammonia, turpentine, and belladonna—a poisonous plant in the deadly nightshade family—for relief from colic spasms. Belladonna is still used modern medicines for adults (it's the main ingredient in the drops your eye doctor uses to dilate your eyes), but according to the FDA, “there is no known safe dose or toxic dose of belladonna in children.” In 2010, the FDA warned against its use in homeopathic teething tablets.

9. LEECHES FOR EARACHES

Merck's 1899 Manual of the Materia Medica, Internet Archive // Public Domain

Using leeches for an ear infection might sound disgusting at best, but there was some medical justification for the manual's recommendation. Once leeches are firmly attached to their host, they can numb pain, while peptides and proteins in their saliva prevent blood clotting, so they can help drain an infection. Modern medicine has recently taken another look at leeches: In 2004, the FDA decided the creatures met the definition of a live medical device, since their tiny jaws (and anticoagulants) keep blood flowing, which helps wounds to heal. They can also be used to break up blood clots, treat varicose veins, and improve other circulatory disorders.

10. COCAINE FOR ALCOHOLISM

Merck's 1899 Manual of the Materia Medica, Internet Archive // Public Domain

In the 1880s, Sigmund Freud helped popularize the idea of using cocaine to treat alcoholism, calling it a “magical drug.” In its heyday, cocaine was also promoted as a cure for morphine addiction, depression, anxiety, fatigue, and migraines. It was available over the counter in tonics, powders, wines, and soft drinks. Patients likely felt energized by regular cocaine infusions, but they soon became habituated. (Freud experimented on himself for a few years until the mounting evidence of cocaine’s addictive nature proved too much to ignore; the drug was made illegal in the U.S. in 1914.) The 1899 manual also offered simpler, less dangerous—but also likely ineffective—ways to battle alcohol cravings, including slowly sucking an orange or drinking water hot ("one pint drunk as hot as possible an hour before meals will remove craving"), or cold in small sips.