All-trans retinoic acid (tretinoin) belongs to a group of medications known as retinoids. It kills certain types of cancer cells by interfering with their growth and reproduction. It is used to treat a type of leukemia (cancer of the white blood cells) known as acute promyelocytic leukemia (APL).

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended dose of all-trans retinoic acid is calculated based on body size. Your doctor will calculate the daily starting dose as 45 mg per square metre of body surface area, a measurement that combines your height and weight. This dose should be divided into two equal doses and taken approximately 12 hours apart. If side effects are severe, your doctor may reduce the dose.

All-trans retinoic acid is taken twice a day for 30 to 90 days, until the cancer is under control (remission).

Medications (retinoids) in this class are often absorbed more easily with food. For this reason, all-trans retinoic acid should be taken with a meal or shortly after a meal.

Many things can affect the dose and schedule of medication that a person needs, such as body weight, other medical conditions, and other medications. The schedule chosen by your doctor may differ from the one mentioned here.

All-trans retinoic acid often causes fever, headache, tiredness, and weakness, but it is important to keep using this medication even if you feel ill, unless otherwise directed by your doctor. Keep track of any side effects and report them to your doctor as suggested in the section "What side effects are possible with this medication?"

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose of this medication, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature in its original packaging, protect it from light and moisture, and keep it out of the reach of children.

Each oval-shaped, soft gelatin capsule, one half reddish-brown opaque and the other half brownish-yellow opaque, contains tretinoin 10 mg. Nonmedicinal ingredients: gelatin, glycerol, hydrogenated hydrolyzed starch, hydrogenated soybean oil, iron oxide, mannitol, partially hydrogenated soybean oil, sorbitol, soybean oil, titanium dioxide, and yellow beeswax.

Do not take all-trans retinoic acid if you:

• are allergic to all-trans retinoic acid, any related compounds, or any ingredients of the medication
• are breast-feeding
• are pregnant or could become pregnant (unless you have practiced effective contraception for at least one month prior, during, and one month after discontinuation of therapy)
• are taking any other form of vitamin A

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• anxiety, restlessness
• appetite loss
• burning, crawling, or tingling feeling in the skin
• clumsiness with walking
• confusion
• constipation
• diarrhea
• dizziness
• dry mouth, lips, or nose
• dry skin
• fatigue
• fever
• flushing
• forgetfulness
• hair loss
• headache
• indigestion
• itchiness
• muscle pain
• nausea
• shivering or trembling
• sleeping problems
• tiredness
• vomiting
• weakness in the legs
• weight loss

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• abdominal pain
• changes in vision that aren't accompanied by headache
• coughing
• cracked lips
• crusting, redness, pain, or sores in the mouth or nose
• earache
• pain and swelling in the leg or foot
• pain in lower back or side
• rash
• shortness of breath
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of kidney problems (e.g., decreased urination, difficult or painful urination, pain in the lower back or side, blood in the urine)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of a blood clot in blood vessels, such as sudden vision change or dizziness, chest pain, pain and swelling in one leg muscle
• signs of too much Vitamin A (e.g., dry mouth, dry skin, rash, nausea, vomiting, bone pain)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• bone pain
• chest tightness or wheezing
• dizziness, lightheadedness, low blood pressure, or feeling faint
• nausea and vomiting with a headache
• seizures
• signs of a blood clot in the arm or leg (tenderness, pain, swelling, warmth, or redness in the arm or leg) or lungs (difficulty breathing, sharp chest pain that is worst when breathing in, coughing, coughing up blood, sweating, or passing out)
• signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• signs of a heart attack (e.g., chest pain or pressure, pain extending through shoulder and arm, nausea and vomiting, sweating)
• signs of stroke (e.g., sudden headache, weakness or numbness in an arm or leg, difficulty speaking or understanding, sudden vision difficulty, dizziness)
• signs of retinoic acid syndrome (e.g., fever, shortness of breath, swelling or puffiness of the arms, legs and feet, weight gain, difficulty in urination, yellowing of the skin or eyes)
• vision problems with a headache

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Birth control: Effective birth control should be practiced while using this medication as this medication may harm the baby if used during pregnancy. For women capable of becoming pregnant, effective birth control must be in place at least one month before starting this medication. Treatment should not begin until the second or third day of the next normal menstrual period. A negative pregnancy test result must be obtained within the 2 weeks before starting treatment.

Birth control should be continued for at least one month after stopping this medication.

Blood clots: This medication may increase the chance of blood clot formation, causing reduction of blood flow to organs or the extremities.

If you have a history of clotting you may be at increased risk of experiencing blood clot-related problems such as heart attack, stroke, or clots in the deep veins of your leg. Discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms such as sharp pain and swelling in the leg, difficulty breathing, chest pain, blurred vision or difficulty speaking, contact your doctor immediately.

Dizziness/reduced alertness: All-trans retinoic acid may affect the mental or physical abilities needed to drive or operate machinery, particularly if it is causing severe headache or dizziness. Avoid driving, operating machinery, or performing other hazardous tasks until you have determined how this medication affects you.

Retinoic Acid Syndrome: This medication can cause a number of symptoms related to the over-production of white blood cells. Although this condition can be corrected if it is identified early, it can cause the failure of multiple organs in the body and become fatal if not treated appropriately. If you experience fever; shortness of breath; dizziness or fainting; swelling of the hands, feet and ankles; or sudden weight gain, contact your doctor immediately.

Pregnancy: All-trans retinoic acid is associated with a very high risk of birth defects if taken during pregnancy. Therefore, this medication should not be used during pregnancy, and effective birth control must be used. If you become pregnant while using this medication, contact your doctor immediately.

Breast-feeding: It is not known if all-trans retinoic acid passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. It is recommended that women not breast-feed while receiving all-trans retinoic acid treatment due to risk of harm to the infant.

There may be an interaction between all-trans retinoic acid and any of the following:

• aldesleukin
• alpha blockers (e.g., alfuzosin, terazosin)
• aliskiren
• amiodarone
• angiotensin-converting enzyme inhibitors (ACEIs; e.g., captopril, ramipril)
• angiotensin receptor blockers (ARBs; e.g., candesartan, irbesartan, losartan)
• antipsychotics (e.g., aripiprazole, brexpiprazole, clozapine)
• aripiprazole
• "azole" antifungals (e.g., itraconazole, ketoconazole, voriconazole)
• barbiturates (e.g., phenobarbital, secobarbital)
• beta-adrenergic blockers (e.g., atenolol, bisoprolol, metoprolol)
• brimonidine
• bromocriptine
• calcium channel blockers (e.g., amlodipine, diltiazem, verapamil)
• carbamazepine
• clarithromycin
• clonidine
• cobicistat
• conivaptan
• diuretics (water pills; e.g., furosemide, hydrochlorothiazide)
• duloxetine
• guanfacine
• HIV protease inhibitors (e.g., atazanavir, darunavir, lopinavir, nelfinavir, ritonavir, saquinavir)
• hydralazine
• indinavir
• levodopa
• mifepristone
• morphine
• multivitamins
• nabilone
• nitrates (e.g., isosorbide dinitrate, nitroglycerin)
• pramipexole
• progesterone-only birth control (e.g., drospirenone, norethindrone)
• rasagiline
• tamsulosin
• tetracyclines (e.g., doxycycline, minocycline, tetracycline)
• tizanidine
• tranexamic acid
• tranylcypromine
• vardenafil
• vitamin A

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, decongestants, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.