Tretinoin, also known as all-trans retinoic acid (ATRA), is a medication used for the treatment of acne and acute promyelocytic leukemia.

[10] For acute promyelocytic leukemia, it is effective only when the RARA-PML fusion mutation is present[11] and is taken by mouth for up to three months.

[10] When taken by mouth, side effects include hypertriglyceridemia, hypercholesterolemia, shortness of breath, headache, numbness, depression, skin dryness, itchiness, hair loss, vomiting, muscle pains, and vision changes.

In human skin, topical retinoids increase collagen production, induce epidermal hyperplasia, and decrease keratinocyte and melanocyte atypia.

[24] Tretinoin is used to induce remission in people with acute promyelocytic leukemia (APL) who have a mutation (the t(15;17) translocation that gives rise to the PML::RARα fusion gene).

Preclinical studies and clinical data analysis suggest that retinoic acid promotes the growth of T-cell acute lymphoblastic leukemia.

[5] Other significant side effects include a risk of thrombosis, benign intracranial hypertension in children, high lipids (hypercholesterolemia and/or hypertriglyceridemia), and liver damage.

[5] There are many significant side effects from this drug that include malaise (66%), shivering (63%), hemorrhage (60%), infections (58%), peripheral edema (52%), pain (37%), chest discomfort (32%), edema (29%), disseminated intravascular coagulation (26%), weight increase (23%), injection site reactions (17%), anorexia (17%), weight decrease (17%), and myalgia (14%).

[5] Gastrointestinal disorders include bleeding (34%), abdominal pain (31%), diarrhea (23%), constipation (17%), dyspepsia (14%), and swollen belly (11%) and many others at less than 10%.

[5] Cardiovascular side effects include arrhythmias (23%), flushing (23%), hypotension (14%), hypertension (11%), phlebitis (11%), and cardiac failure (6%) and for 3% of patients: cardiac arrest, myocardial infarction, enlarged heart, heart murmur, ischemia, stroke, myocarditis, pericarditis, pulmonary hypertension, secondary cardiomyopathy.

[5] In the nervous system, side effects include dizziness (20%), paresthesias (17%), anxiety (17%), insomnia (14%), depression (14%), confusion (11%), and many others at less than 10% frequency.

The RARA:PML oncogene is not present in other cancer types, thus explaining why tretinoin and other retinoids have not been effective across hundreds of different trials.

[citation needed] All-trans retinoic acid is produced by the body from dietary factors including retinol, retinyl esters or beta-carotene.

[38] Treatment of acute promyelocytic leukemia was first introduced at Ruijin Hospital in Shanghai by Wang Zhenyi in a 1988 clinical trial.