 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  a long time, this medication may not work as well. Talk with your doctor if this medication stops working well. Though it helps many people, this medication may sometimes cause addiction. This risk may be higher if you have a substance use disorder (such as overuse of or addiction to drugs/alcohol). Take this medication exactly as prescribed to lower the risk of addiction. Ask your doctor or pharmacist for more details. Tell your doctor if your condition does not improve or if it worsens.The side effects of Methylphenidate HCl Oral: 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 </s>