Heart problems. Koselugo can lower the amount of blood pumped by your heart, which is common and can also be severe. Your healthcare provider will do tests before and during treatment with Koselugo to check how well your heart is working. Tell your healthcare provider right away if you get any of the following signs or symptoms:
persistent coughing or wheezing
shortness of breath
swelling of your ankles and feet
increased heart rate
Eye problems. Koselugo can cause eye problems that can lead to blindness. Your healthcare provider will check your vision before and during treatment with Koselugo. Tell your healthcare provider right away if you get any of the following signs or symptoms:
loss of vision
dark spots in your vision (floaters)
other changes to your vision
Severe diarrhea. Diarrhea is common with Koselugo and can also be severe. Tell your healthcare provider right away the first time that you get diarrhea during treatment with Koselugo. Your healthcare provider may give you medicine to help control your diarrhea and may tell you to drink more fluids.
Skin rash. Skin rashes are common with Koselugo and can also be severe. Tell your healthcare provider if you get any of the following signs or symptoms:
rash that covers a large area of your body
Muscle problems (rhabdomyolysis). Muscle problems are common with Koselugo and can also be severe. Treatment with Koselugo may increase the level of a muscle enzyme in your blood, which may be a sign of muscle damage. Your healthcare provider should do a blood test to check your muscle enzyme levels before you start taking Koselugo and during treatment. Tell your healthcare provider right away if you get any of the following signs or symptoms:
muscle aches or pain
muscle spasms and weakness
dark, reddish urine
Your healthcare provider may change your dose, temporarily stop, or permanently ask you to stop taking Koselugo if you have any of these side effects.
have heart problems
have eye problems
are pregnant or plan to become pregnant. Koselugo can harm your unborn baby
Females who could become pregnant and males with female partners who could become pregnant should use effective birth control (contraception) during treatment with Koselugo and for 1 week after your last dose
Tell your healthcare provider right away if you become pregnant during treatment with Koselugo, are breastfeeding, or plan to breastfeed. It is not known if Koselugo passes into your breast milk
Do not breastfeed during treatment with Koselugo and for 1 week after your last dose
Talk to your healthcare provider about the best way to feed your baby during this time
Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, or herbal supplements. Especially tell your healthcare provider if you are taking aspirin, blood thinners, or other medicines to treat blood clots. Koselugo contains vitamin E, which may increase your risk of bleeding.
feeling of tiredness, weakness, or lacking energy
muscle and bone pain
inflammation of the mouth
redness around the fingernails
These are not all the possible side effects of Koselugo.
Koselugo is a prescription medicine that is used to treat children 2 years of age and older with neurofibromatosis type 1 (NF1) who have plexiform neurofibromas that cannot be completely removed by surgery.
It is not known if Koselugo is safe and effective in children under 2 years of age.