An employee was climbing a telecommunications tower without incident. A co-worker looked over and the employee appeared to be in pain while holding on to the tower at a height of approximately 250 feet. No fall or other event occurred. The employee just climbed the tower and started feeling pain in his lower back. Tower rescue was initiated and the employee was lowered to the ground. The employee was using a personal fall arrest system and was fully tied-off when he experienced the pain. Upon reaching the ground, an emergency response crew began administering pain medication. The employee experienced an adverse reaction to the medication and was rushed to the hospital where he was admitted primarily due to his reaction to the medication administered by the first responders, but the employee may have some lower back disorder(s) as well.