Despite the following occurrences, Lincoln's health up until middle age was fairly good for his day.
There were fears for young Lincoln's life during a 24-hour period of unconsciousness that followed a horse kicking him in the head. He was nine years old. On another occasion, he fell into a creek and almost drowned.
Malaria: Lincoln had malaria at least twice. The first was in 1830, along with the rest of his family. They had just arrived in Illinois that year. The second episode was in the summer of 1835, while living in New Salem. Lincoln was then so ill, he was sent to a neighbor's house to be medicated and cared for.
Syphilis: Claims that Lincoln had syphilis about 1835 have been controversial. The most recent analysis by a physician accepts the diagnosis. All biographers reject the claim. Lincoln's law partner William Herndon said Lincoln contracted the disease, specifically stating that "Lincoln told me this." There is no physical evidence that Lincoln had the disease, but physical evidence would not necessarily be expected, given that 50% of infections do not progress beyond a transient local infection, even without treatment. Syphilis was a common worry among young men before the introduction of penicillin but this is not unexpected, given the commonness of syphilis in that era. Writing in 2003, biographer David Donald declared "Modern physicians who have sifted the evidence agree that Lincoln never contracted the disease," however, these physicians have never published their analyses.
Smallpox: Lincoln contracted smallpox shortly after delivering the Gettysburg Address in November 1863. Long thought to have been only a mild case, recent work suggests it was a serious illness. Although it did not debilitate Lincoln, the disease did significantly affect his White House routine, and limited the advisors with whom he could meet.
Lincoln died from a bullet wound to the head in 1865. His other episodes of adult trauma were minor. He was clubbed on the head during a robbery attempt in 1828, was struck by his wife (apparently on multiple occasions), cut his hand with an axe at least once, and incurred frostbite of his feet in 1830-1831.
The shape ("habitus") of Lincoln's body attracted attention while he was alive, and continues to attract attention today among medical professionals. Geneticists are now skeptical of the hypothesis that Marfan syndrome was the cause of his unusual habitus (see below).
Weight: Although well-muscled as a young adult, he was always thin. Questionable evidence says Lincoln weighed over 200 pounds (90 kg) in 1831, but this is inconsistent with the emphatic statement of Henry Lee Ross ("The facts are Lincoln never weighed over 175 pounds in his life"), the recollection of David Turnham ("weighed about 160 lbs in 1830"), and a New Salem neighbor named Camron ("thin as a beanpole and ugly as a scarecrow"). Lincoln's self-reported weight was 180 lbs (81.5 kg) in 1859. He is believed to have weighed even less during his presidency.
Marfan syndrome: Based on Lincoln's unusual physical appearance, Dr. Abraham Gordon proposed in 1962 that Lincoln had Marfan syndrome. Testing Lincoln's DNA for Marfan syndrome was contemplated in the 1990s, but such a test was not performed.
Lincoln's unremarkable cardiovascular history and his normal visual acuity have been the chief objections to the theory, and today geneticists consider the diagnosis unlikely.
Multiple Endocrine Neoplasia: In 2007, Dr. John Sotos proposed that Lincoln had multiple endocrine neoplasia type 2b (MEN2B). This theory suggests Lincoln had all the major features of the disease: a marfan-like body shape, large, bumpy lips, constipation, hypotonia, a history compatible with cancer – to which Sotos ascribes the death of Lincoln's sons Eddie, Willie, and Tad, and probably his mother. The "mole" on Lincoln's right cheek, the asymmetry of his face, his large jaw, his drooping eyelid, and "pseudo-depression" are also suggested as manifestations of MEN2B. MEN2B is a genetic disorder, and recently it has been demonstrated that Lincoln's biological mother, Nancy Hanks Lincoln, had many of the same unusual facial features as her son, as well as a marfanoid body habitus. Lincoln's longevity is the principal challenge to the MEN2B theory: Lincoln lived long enough to be assassinated at age 56, while untreated MEN2B is generally understood to result in death by the patient's mid-thirties. There are, however, several reported cases of MEN2B patients surviving into their 50s with no or little treatment. The theory could be proven by DNA testing.
The theory that Lincoln was afflicted with type 5 spinocerebellar ataxia is no longer accepted. The theory that Lincoln's facial asymmetries were a manifestation of craniofacial microsomia has been replaced with a diagnosis of left synostotic frontal plagiocephaly, which is a type of craniosynostosis.
Lincoln was contemporaneously described as suffering from "melancholy," a condition which modern mental health professionals would characterize as clinical depression.
It was during his time as an Illinois legislator that Joshua Speed said Lincoln anonymously published a suicide poem in the Sangamo Journal; though he was not sure of the date, a suicide poem was published on August 25, 1838, making Lincoln 29 years of age. The poem is called The Suicide's Soliloquy; historians are still divided on whether or not Lincoln was the author.
Whether he may have suffered from depression as a genetic predilection, as a reaction to multiple emotional traumas in his life, or a combination thereof is the subject of much current conjecture.
Lincoln suffered depressed mood after major traumatic events, such as the death of Ann Rutledge in August 1835, the cessation of his (purported) engagement to Mary Todd Lincoln in January 1841 (after which several close associates feared Lincoln's suicide), and after the Second Battle of Bull Run. However, it is not clear that any of these episodes meet modern medical criteria for depression.
Mary Lincoln felt her husband to be too trusting, and his melancholy tended to strike at times he was betrayed or unsupported by those in whom he put faith.
Lincoln would often combat his melancholic moods by delving into works of humor, likely a healthy coping mechanism for his depression.
It has been proposed that Lincoln took "blue mass" pills to improve his mood. There is, however, no support for this in the written record. (See "Medication" section, below.)
The recollections of Lincoln's legal colleagues (John Stuart, Henry Whitney, Ward Lamon, and William Herndon) all agree that Lincoln took blue mass pills because of constipation (constipation is a troubling symptom in Multiple Endocrine Neoplasia Type 2B, described above). The active ingredient of blue mass is elemental mercury – a substance now known to be a neurotoxin in its vaporic state. Whether mercury poisoning may have affected Lincoln's demeanor before or after he ceased its use in 1861 is unknown, but still remains the subject of conjecture by some historians. Lincoln's only known assessments of the medication are that it made him "cross" but that he preferred it above others.
In 1865, speaking with the Washington correspondent of the Pittsburgh Chronicle, Mrs. Lincoln described an instance in which her husband's "usual medicine," the mercury based "blue pills" made him terribly ill. The correspondent recorded the interview as follows: Mrs. Lincoln "recalled the fact that her husband had been very ill, for several days, from the effects of a dose of blue pills taken shortly before his second inauguration." She said he was not well, and appearing to require his usual medicine, blue pills, she sent to the drug store in which Harrold was employed last and got a dose and gave them to him at night before going to bed, and that next morning his pallor terrified her. 'His face,' said she, pointing to the bed beside which she sat, 'was white as that pillow-case, as it lay just there,' she exclaimed, laying her hand on the pillow—'white, and such a deadly white; as he tried to rise he sank back again quite overcome!' She described his anxiety to be up, there was so much to do, and her persistence and his oppressive languor in keeping him in bed for several days; said he and she both thought it so strange that the pills should affect him in that way; they never had done so before, and both concluded they would get no more medicine there, as the attendant evidently did not understand making up prescriptions."