“Be careful about reading health books—you may die of a misprint”

“Be careful about reading health books—you may die of a misprint” has been credited since the 1970s to the American writer Mark Twain (1835-1910), but there’s no evidence that Twain either wrote or said it. The American physician and poet Oliver Wendell Holmes, Sr. (1809-1894) received credit in the 1930s, but there’s no evidence that Holmes wrote or said it, either.
 
The Jewish German physician Marcus Herz (1747-1803) was reported in the 1840s to have remarked about copied prescriptions of printed formulae, “My dear friend, an error of the press will assuredly, some day or other, be the death of you.” The book The Hygiene of the Soul: Memoir of a Physician and Philosopher (1910) phrased the Herz quote to someone who overly relied on medical books, “My dear fellow, you will some day die of a misprint.” The 1910 book quotation was reprinted in many American newspapers.
 
   
Wikipedia: Marcus Herz
Marcus (Markus) Herz (January 17, 1747 – January 19, 1803), was a Jewish German physician and lecturer on philosophy.
 
Wikiquote: Talk:Mark Twain
You may die of a misprint
Das sind jene kleinlichen Unglücklichen, von welchen ich in einem früheren Absatze sagte, daß sie der Arzt selbst verachten müsse, den sie ewig konsultieren; das sind jene freiwilligen Kandidaten der Medizin, die sich in die ganze Krankheitslehre hineinlesen, die sich aus Büchern Rezepte verschreiben, zu deren einem Markus Herz, der berühmt gewordene Feind alles Schwindels, einmal sagte: Lieber Freund! Sie werden noch einmal an einem Druckfehler sterben!
. Ernst von Feuchtersleben, Zur Diätetik der Seele (1841), p. 95.

These are the weak-minded persons, of whom I remarked, in a former chapter, that even the physician whom, they constantly seek must despise them. These men become volunteers in the ranks of medicine; they overload their minds with whole courses of physic; they copy prescriptions from printed formulae; and it was to one of this class that Marcus Herz once wittily remarked, “My dear friend, an error of the press will assuredly, some day or other, be the death of you.”
. Ernst von Feuchtersleben, Dietetics of the Soul (1851), p. 127

Does not the hypochondriac die daily from fear of death? Nothing is more pathetically ludicrous than to see these petty unfortunates who ransack medical books in order to copy prescriptions and rules for the preservation of health. To one of these Dr. Herz once said: “My dear fellow, you will some day die of a misprint.”
. Gustav Pollak and Ernst von Feuchtersleben, The hygiene of the soul: memoir of a physician and philosopher (1910), p. 101
   
18 November 1910, The Daily Journal (Flint, MI), pg. 4, col. 4:
How We Differ From Doctors.
A book of anecdotes of famous physicians by Gustav Hochstetter and Georg Zehden has been issued in Berlin. Dr. Marcus Herz is credited with saying to a patient who read medical books diligently in order to prescribe for himself:
   
“Be careful, my friend. Some day you’ll die of a misprint.”
(From the Philadelphia Record—ed.)
 
PapersPast
4 March 1911, Feilding (New Zealand) Star, “Some Smile Seeds,” pg. 3:
Dr. Marcus Herz, of Berlin, is credited with sayng to a patient who read medical books diligently in order to prescribe for himself: “Be careful, my friend. Some fine day you’ll die of a misprint.”
 
Google News Archive
21 November 1920, Pittsburg (PA) Press, “Do You Doctor Yourself?” by Public Health Service, Additional News Section, pg. 7, col. 5:
“I doctor myself by the aid of medical books.”
“Yes and some day you’ll die of a misprint.”—Boston Transcript.
 
Google Books
Help your doctor to help you when you have food allergy
By Walter C. Alvarez
New York, NY: Harper
1941
Pg. VII:
As Oliver Wendell Holmes once said to a worrisome patient whom he found in the medical library reading up on his disease, “Look out, or you’ll die of a misprint some day!”
 
28 January 1955, Rockford (IL) Register-Republic, “Dr. Alvarez Reports: Read About Disease” by Dr. Walter C. Alvarez, pg. 16B, col. 4:
One evening, as Dr. Oliver Wendell Holmes was going through the Boston Medical library, he spied one of his more worrisome patients seated at a table, reading up on his disease. Holmes touched him on the shoulder and said, “Look out, old man, you may die of a misprint some day!”
 
28 May 1974, The Bakersfield Californian (Bakersfield, CA), “No whiz at math” by Stan Delaplane, pg. 4, col. 1:
“Be careful of the medical books you read,” said Mark Twain. “You might die of a misprint.”
 
18 August 1980, Seattle (WA) Times, Walt Evans column, pg. B2, col. 1:
And along the way they picked up some sage advice from Mark Twain, spotted in a San Francisco store: “Be careful about reading health books—you might die of a misprint.” Sage advice.
 
Google Books
The 2,548 Best Things Anybody Ever Said
By Robert Byrne
New York, NY: Fireside
2002
No. 313:
Be careful about reading health books. You may die of a misprint. —Mark Twain (1835–1910)
   
Google Books
The Thinking Person’s Guide to Fitness
By Jake Nash
CreateSpace
2010
Pg. 4:
Be careful about reading health books. You may die of a misprint. ‐ Mark Twain
Yes, that’s quite a way to start out a health and fitness book, but what Mark Twain knew over a hundred years ago is as true today as it was then.