Some of the most severe are:

serious infections
reactivation of hepatitis B
reactivation of tuberculosis
lethal hepatosplenic T-cell lymphoma (generally only when combined with 6-mercaptopurine)
drug-induced lupus
demyelinating central nervous system disorders
psoriasis and psoriasiform skin lesions
new-onset vitiligoCases of leukopenia, neutropenia, thrombocytopenia, and pancytopenia (some fatal) have been reported with infliximab. The FDA issued a warning to doctors appearing in the respective product labeling of infliximab instructing them to screen and monitor potential patients more carefully. The FDA issued a warning to doctors that there is an increased risk of lymphoma and other cancers associated with the use of infliximab and other tumor necrosis factor blockers in children and adolescents.Maintenance therapy with the drug (versus intermittent or sporadic therapy) lessens the likelihood of developing antibodies to infliximab which are known to reduce the efficacy of the drug. Combination treatment with methotrexate (an antifolate drug which suppresses the immune system) has been shown to reduce the formation of these antibodies in patients with rheumatoid arthritis and combination therapy with other immunosuppressants has been shown to reduce the likelihood of these antibodies being formed in Crohns disease. The use of immunosuppressants may not be necessary in all diseases for which infliximab is indicated, and indiscriminant uses of these other immunosuppressants carry their own risks. Infliximab was studied in monotherapy (without concomitant immunosuppressants such as methotrexate or azathioprine) in psoriasis, psoriatic arthritis, and ankylosing spondylitis.
Complimentary and alternative medicine
No clear beneficial effect from spinal manipulation or massage has been shown. Further, as there is no evidence of safety for cervical manipulation for baby colic, it is not advised. There is a case of a three-month-old dying following manipulation of the neck area.Little clinical evidence supports the efficacy of "gripe water" and caution in use is needed, especially in formulations that include alcohol or sugar. Evidence does not support lactase supplementation. The use of probiotics, specifically Lactobacillus reuteri, decreases crying time at three weeks by 46 minutes in breastfeed babies but has unclear effects in those who are formula fed. Fennel also appears effective. Prognosis
Infants who are colicky do just as well as their non colicky peers with respect to temperament at one year of age. Epidemiology
Colic affects 10–40% of children, occurring at the same rate in boys and in girls. History
The word "colic" is derived from the ancient Greek word for intestine (sharing the same root as the word "colon").It has been an age-old practice to drug crying infants. During the second century AD, the Greek physician Galen prescribed opium to calm fussy babies, and during the Middle Ages in Europe, mothers and wet nurses smeared their nipples with opium lotions before each feeding. Alcohol was also commonly given to infants.In past decades, doctors recommended treating colicky babies with sedative medications (e.g. phenobarbital, Valium, alcohol), analgesics (e.g. opium) or anti-spasm drugs (e.g. scopolamine, Donnatal, dicyclomine), but all of these are no longer recommended because of potential serious side-effects, including death.