Headache or swelling of arms/legs may occur. If either of these effects lasts or gets worse, tell your doctor or pharmacist promptly.
Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
This medication may raise your blood pressure. Check your blood pressure regularly and tell your doctor if the results are high.
This medication may rarely cause serious liver disease. Tell your doctor right away if you have any symptoms of liver disease, such as: nausea/vomiting that doesn't stop, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine.
This medication can weaken your immune system/increase the risk of infection while you are taking it and for 3 to 4 weeks after your last dose. You may be more likely to get a serious (possibly fatal) infection (such as bronchitis, herpes). Tell your doctor right away if you develop any signs of an infection such as sore throat/cough that doesn't go away, difficulty breathing, fever/chills, cold/flu symptoms, sores, or blisters. Do not start siponimod if you already have an infection.
This medication may increase your risk of getting a rare but very serious (possibly fatal) brain infection (progressive multifocal leukoencephalopathy-PML). Symptoms of PML can seem like a worsening MS attack. Get medical help right away if you have any new or worsening symptoms that have lasted for several days, such as clumsiness or problems with strength, balance, speech, eyesight, or thinking.
Siponimod may rarely increase your risk of skin cancer. Tell your doctor right away if you notice any unusual skin changes (such as change in appearance/size of moles).
Get medical help right away if you have any very serious side effects, including: shortness of breath, slow/irregular/pounding/fast heartbeat, severe dizziness/fainting, unusual tiredness/weakness, eye pain/sensitivity to light, vision changes (such as blurred vision, blind spot/shadows in the center of your vision, color changes), mental changes (such as sudden confusion), seizure, sudden/severe headache.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.