Depending upon several different factors, morphine usually remains in the system for one to four days. However, morphine usage can be detected by certain types of drug tests for up to three months.
According to L'université de Lausanne, the half-life of morphine is approximately two hours, which means that it takes two hours for morphine to lose half of its strength. When delivered by injection, the effects of morphine last for three to four hours. When given orally, it can last for three to six hours. Withdrawal symptoms from morphine may begin within six to 14 hours after administration of the last dose.
Urinalysis can detect morphine up to four days after the drug was used. Blood tests are effective if testing occurs within 12 hours of use of the drug, and saliva tests can detect morphine for up to four days. Hair follicle tests can determine if morphine was used within the last 90 days.