A person's history of taking paracetamol is somewhat accurate for the diagnosis.  The most effective way to diagnose poisoning is by obtaining a blood paracetamol level. A drug nomogram developed in 1975, called the Rumack-Matthew nomogram , estimates the risk of toxicity based on the serum concentration of paracetamol at a given number of hours after ingestion.  To determine the risk of potential hepatotoxicity, the paracetamol level is traced along the nomogram. Use of a timed serum paracetamol level plotted on the nomogram appears to be the best marker indicating the potential for liver injury.  A paracetamol level drawn in the first four hours after ingestion may underestimate the amount in the system because paracetamol may still be in the process of being absorbed from the gastrointestinal tract . Therefore, a serum level taken before 4 hours is not recommended. 
Studies have shown that people who take anti-inflammatory painkillers have a small but significant increase in the risk of developing a heart attack or stroke . Although it can occur in anybody, the risk is mainly in people already known to have cardiovascular problems such as angina or peripheral arterial disease , and in the elderly. Perhaps the highest risk is in people who have previously had a heart attack. For example, one research study looked at people who had previously had a heart attack. The results showed a marked increase in the rate of a second heart attack in people who were taking an anti-inflammatory compared to those who were not.