The Andrew Johnson alcoholism debate is the dispute, originally conducted amongst the general public, and now typically a question for historians, about whether or not Andrew Johnson, the 17th president of the United States, drank to excess. There is no question that Andrew Johnson consumed alcohol (as would have been typical for any Tennessean of his era and station). The debate concerns whether or not he was governing drunk, how alcohol may have altered his personality and disrupted his relationships, and if, when, or how it affected his political standing, and his current bottom-quartile historical assessment. Less so today, but in his own time, Johnson's alleged drinking contributed substantially to his peers evaluation of his "attributes of mind, character, and speech...where the good ruler is temperate, Johnson is an inebriate; where the good ruler is selfless, Johnson is self-regarding; where the good ruler is eloquent, Johnson is a rank demagogue...behind all these assumptions is the still and silent image of the Great Emancipator, but that is another story."

The Andrew Johnson alcoholism debate may be a case of questions without answers. Per historian Annette Gordon-Reed, "We will probably never know the extent to which alcohol was a part of Johnson's life. Not all alcoholics appear drunk in public, and his relatively solitary existence—his family was almost never with him and he had few friends—was exactly the kind of setup that allowed for unobtrusive drinking that could become a problem in a time of great emotional and physical stress."

We tell them we would sooner have Andy Johnson drunk than Jeff. Davis sober, or John Breckenridge either, if he could be ever found sober.

— Rev. Dr. Hancock's Temperance Address, New York, June 1865, Buffalo Advocate

According to two histories of alcohol in the United States, the country had three alcoholic presidents during the 19th century: Franklin Pierce, Andrew Johnson, and Ulysses S. Grant. A broad overview of the human use of intoxicants asserts that Johnson was thought to "be rarely sober." A scholarly examination of the consequences of illness in national leaders states, "The best-known instance of alcohol abuse in high office is that of Andrew Johnson, whose alcoholism figured in the debate concerning his impeachment."

"Drunkenness, of Johnson" has 16 mentions in Andrew Johnson: A Biographical Companion, which puts the topic on par with "Election of 1866" and "First Military Reconstruction Act." The Biographical Companion, citing the editors of The Papers of Andrew Johnson and Hans Trefousse, states that all charges/claims of Johnson being drunk "were false except for one incident [the March 4 inauguration]...Johnson was not intoxicated. He was merely falling back into ingrained stump-speaking habits...His actions did not conform to many people's ideas about how a president should behave." The most famous case of Andy drunk was at his 1865 vice-presidential inauguration, but it was not the first or the last time he appeared intoxicated in public, and per historian Elizabeth R. Varon, "He never lived these incidents down, although historians contend that they were greatly exaggerated." As he set out on his Swing Around the Circle tour as president, a Pennsylvania newspaper summarized the general perception (amongst his enemies, at least) of the intersection of Johnson's drinking and his politics: "From the day that Andrew Johnson took his seat as Vice President of the United States to the present moment he seems to have improved every opportunity to belittle himself and disgrace the position he holds, by either bacchanalian revels, or the retailing of vile slang in partisan speeches...His stooping to blackguard private citizens was thought to be lowest depth to which drunken recklessness could drag him down, but a lower depth has been found." A 1916 thesis on Johnson's era as military governor of Tennessee argued, "The habit of indulging in intoxicants, afterwards reputed as Johnson's most conspicuous personal failing as President, had, of course, been formed long before. There is no evidence that it interfered seriously with the performance of his duties, but it occasionally betrayed him into extravagance of action and expression which did him no credit."

Nonetheless, after examining recollections of Johnson by Vice President Hannibal Hamlin and Interior Secretary Carl Schurz, historian of alcoholism James Graham found that Andrew Johnson most likely met the criteria for problem drinking, based on accounts that suggest he indulged in benders, drank in "enormous" quantities, gulped down hard liquor as if it were water, drank in the morning, drank after drinking, and consumed excessive, inebriating quantities of alcohol at inappropriate times. Graham argues that "ugly behavior is symptomatic," and states that "It's probable that [Johnson's] alcoholism-driven ego played a more important role in his clash with Congress, which led to the attempted impeachment, than alcoholism-ignorant modern historians realize." He also argues that alcoholism is often "not noticed outside the home until the alcoholic reaches the advanced stage of the disease and starts showing the bizarre behavior associated with the condition—such as showing up drunk on the job."

Given that alcoholism in family systems continues to be a subject of addiction research, it may be relevant that all three of Johnson's sons struggled with alcoholism, quite publicly in the case of Robert Johnson—he was in the New York State Inebriate Asylum at the time of Grant's inauguration. Robert died of an overdose of alcohol and laudanum, but by some historians theorize that alcohol was also involved in the youthful deaths of Charles and Frank, which are otherwise attributed to accident and tuberculosis, respectively. Further, there are suggestions that David T. Patterson, who was married to Johnson's daughter Martha, had a drinking problem. During the impeachment process, Andrew Johnson himself wrote, "I have had a son killed, a son-in-law die during the last battle at Nashville, another son has thrown himself away, a second son-in-law is in no better condition. I think I have had sorrow enough without having my bank account examined by a Committee of Congress," referring to Charles, Dan Stover, Robert, and Patterson (a sitting U.S. Senator), respectively. In 1891, three months before Patterson's death, a newspaper article described him as "fallen before the same terrific curse which swept away the head of [Martha Johnson Patterson's] family and three talented boys." There are also two newspaper reports that William A. Browning, who worked as Johnson's personal secretary for many years, died of alcohol dependence at age 31.