Do not take this medicine with any of the following medications:

-alfuzosin
-certain antivirals for HIV or hepatitis like atazanavir, cobicistat, darunavir, delavirdine, nelfinavir, saquinavir, or tipranavir
-certain medicines for cholesterol like lovastatin or simvastatin
-certain medicines for fungal infections like fluconazole, isavuconazonium, or posaconazole
-conivaptan
-cisapride
-dronedarone
-eletriptan
-eplerenone
-ergot alkaloids like dihydroergotamine or ergotamine
-flibanserin
-fosamprenavir
-ivabradine
-lomitapide
-lurasidone
-naloxegol
-pimozide
-ranolazine
-silodosin
-thioridazine
-tolvaptan
-triazolam
-ubrogepant
This medicine may interact with the following medications:

-alfentanil
-antiviral medicines for HIV or AIDS
-certain medicines for fungal infections like ketoconazole, itraconazole, voriconazole
-certain medicines for seizures like carbamazepine, phenobarbital, phenytoin
-clarithromycin
-cyclosporine
-everolimus
-fentanyl
-grapefruit juice
-midazolam
-nefazodone
-other medicines that prolong the QT interval (cause an abnormal heart rhythm) like dofetilide, ziprasidone
-pomegranate juice
-quinidine
-rifampin
-sirolimus
-St. John''s Wort
-tacrolimus

They need to know if you have any of these conditions:

-heart disease
-history of irregular heartbeat
-infection (especially a virus infection such as chickenpox, cold sores, or herpes)
-liver disease
-low blood counts, like low white cell, platelet, or red cell counts
-low levels of calcium, magnesium, potassium, or phosphorus in the blood
-lung or breathing disease, like asthma
-weak bones
-an unusual or allergic reaction to ribociclib, letrozole, other medicines, foods, dyes, or preservatives
-pregnant or trying to get pregnant
-breast-feeding

Tell your doctor or healthcare professional if your symptoms do not start to get better or if they get worse.
Do not take this medicine close to bedtime. It may prevent you from sleeping.
You may need blood work done while you are taking this medicine.
Do not become pregnant while taking this medicine or for 3 weeks after the last dose. Women should inform their doctor if they wish to become pregnant or think they might be pregnant. There is a potential for serious side effects to an unborn child. Men should inform their doctors if they wish to father a child. This medicine may lower sperm counts. Talk to your health care professional or pharmacist for more information. Do not breast-feed an infant while taking this medicine or for 3 weeks after the last dose.
Avoid taking products that contain aspirin, acetaminophen, ibuprofen, naproxen, or ketoprofen unless instructed by your doctor. These medicines may hide a fever.
Be careful brushing and flossing your teeth or using a toothpick because you may get an infection or bleed more easily. If you have any dental work done, tell your dentist you are receiving this medicine.
Call your doctor or health care professional for advice if you get a fever, chills or sore throat, or other symptoms of a cold or flu. Do not treat yourself. This drug decreases your body''s ability to fight infections. Try to avoid being around people who are sick.
This medicine may increase your risk to bruise or bleed. Call your doctor or health care professional if you notice any unusual bleeding.

Keep out of the reach of children.
Store between 20 and 25 degrees C (68 and 77 degrees F). Keep this medicine in the original container. Throw away any unused medicine after the expiration date.