Misuse or abuse of methylphenidate can result in serious (possibly fatal) heart and blood pressure problems. This medication can be habit-forming and should be used cautiously by people who have mental/mood disorders or a substance use disorder (such as overuse of or addiction to drugs/alcohol). Before using this medication, tell your doctor if you have a personal or family history of a substance use disorder. Do not increase your dose, use it more often, or use it for a longer time or in a different way than prescribed. Doing so may result in a decrease in the effect of this drug, drug dependence, or abnormal thoughts/behavior. Your doctor may monitor you for a while after the medication is stopped, especially if you have taken this drug for a long time or in high doses.

Nervousness, trouble sleeping, loss of appetite, weight loss, dizziness, nausea, vomiting, or headache may occur. If any of these effects last or get 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. Tell your doctor right away if you have any serious side effects, including: signs of blood flow problems in the fingers or toes (such as coldness, numbness, pain, or skin color changes), unusual wounds on the fingers or toes, fast/pounding/irregular heartbeat, mental/mood/behavior changes (such as agitation, aggression, mood swings, abnormal thoughts, thoughts of suicide), uncontrolled muscle movements (such as twitching, shaking), sudden outbursts of words/sounds that are hard to control, vision changes (such as blurred vision), slow healing sores/ulcers on the tips of fingers/toes. Get medical help right away if you have any very serious side effects, including: fainting, seizure, symptoms of a heart attack (such as chest/jaw/left arm pain, shortness of breath, unusual sweating), symptoms of a stroke (such as weakness on one side of the body, trouble speaking, sudden vision changes, confusion). Rarely, males (including young boys and teens) may have a painful or prolonged erection lasting 4 or more hours while using this medication. Caregivers/parents should also be watchful for this serious side effect in boys. If a painful or prolonged erection occurs, stop using this drug and get medical help right away, or permanent problems could occur. Ask your doctor or pharmacist for more details. 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.

Taking MAO inhibitors with this medication may cause a serious (possibly fatal) drug interaction. Avoid taking MAO inhibitors (isocarboxazid, linezolid, metaxalone, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine) during treatment with this medication. Most MAO inhibitors should also not be taken for two weeks before treatment with this medication. Ask your doctor when to start or stop taking this medication. Avoid alcohol when using this medication because it may cause the medication to be released too quickly and increase the risk of side effects. Some brands of this drug may be affected by a change in the amount of acid in your stomach. If you are taking a product to decrease stomach acid (such as antacids, ranitidine, omeprazole), check with your pharmacist to see if your brand may be affected. Methylphenidate is very similar to dexmethylphenidate. Do not use medications containing dexmethylphenidate while using methylphenidate. This medication may interfere with certain medical/lab tests (such as brain scan for Parkinson's disease), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.