Hi, Remylin D is a combination of drugs that are used to treat nerve-related disorders such as peripheral neuropathy. The tablet contains methylcobalamin, alpha-lipoic acid, folic acid, and pyridoxine. The common side effects of Remylin D are nausea, vomiting, headache, dizziness, diarrhea, abdominal pain, and skin rash. However, tiredness and heaviness in the head are not commonly reported side effects of Remylin D. These symptoms could be related to other medical conditions or could be due to the age factor. It is always recommended to consult a doctor before continuing or discontinuing any medication. The doctor will evaluate the patient s overall health condition and check if the symptoms are related to any underlying medical conditions or side effects of the medication. Based on the assessment, the doctor may suggest continuing or discontinuing the medication or may adjust the dose accordingly. Therefore, it is advisable to consult the doctor who prescribed Remylin D to your grandfather and discuss the symptoms he is experiencing. The doctor may suggest further evaluation or adjust the dosage of the medication based on the symptoms and overall health condition of your grandfather. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Priyanka, General & Family Physician