The intravenous administration of more than 30 milligrams of morphine sulphate, or morphine, to a normal adult is likely to cause serious toxic effects, including death, according to DailyMed. However, because morphine is an opiate, determining a standard lethal dose is difficult.
It is believed that infants and children are more sensitive to morphine and other opiates based on their body weight, explains DailyMed. The elderly are also less tolerant to morphine and other opiates.
One serious symptom of taking too much morphine is respiratory depression, which may include cyanosis, Cheyne-Stokes respiration and reduced tidal volume and/or respiratory rate. Other serious symptoms include: clammy and cold skin, hypotension, bradycardia, skeletal-muscle flaccidity, and extreme somnolence that leads to a coma or stupor. Severe intravenous overdose can result in cardiac arrest, circulatory collapse, apnea or death, states DailyMed.
The injection of morphine is used to allay chronic or acute pain, or to supplement anesthesia during surgery, as an analgesic during labor or as a preoperative sedative, according to DailyMed. Morphine may also be administered to patients suffering from acute pulmonary edema to ease anxiety and for its effects on the cardiovascular system, unless the condition is caused by a chemical irritant. It is also a preferred drug for relieving myocardial infarction-related pain.