###Human: I feel tightness in the right side of my body. Why? ###Assistant: Hi. I understand your concern. I need to know more about your symptoms. When and how does it start? Is it increasing day by day or it is the same? Is it associated with any pain or muscle ache? Is it aggravated by activity? Are there any diurnal variations? Is there any back pain or neck pain? Any numbness or loss of sensation? How about urination? Any history of trauma or headache? The most common cause of stiffness on one side of the body is muscle rigidity, also known as muscle tension, which can result in muscle pain. It is characterized by the inability of the muscles to relax normally. We are worried about unilateral stiffness. It could be due to spinal cord or brain-related conditions such as minor stroke or multiple sclerosis, spine injury, etc. For the same you need evaluation, I suggest you should consult your physician. Symptomatic relief includes physiotherapy, isometric exercise, and stretching will help. You also can use hot fomentation or massage to relax your limbs. I hope this helps.