How long a pain injection lasts is mainly related to the composition of the drug and the dosage of the injection, and the duration of action of most pain injections can last for 6-8 hours. The more commonly used pain relief injections in clinical practice are tramadol hydrochloride injection, dulcolax, morphine and so on. Due to different drug ingredients and different injection doses, the duration that pain injections can last varies. Also, each person’s pain tolerance level and sensitivity to pain are different, which can also lead to different duration of the drug. The duration of pain injections is usually about 6-8 hours, so the interval between the use of pain medications in clinical practice is mostly 6 hours or more. However, some pain relief injections can produce drug addiction, and long-term use will make patients dependent, and the duration of drug effects will gradually shorten, resulting in shorter and shorter intervals between drug injections. After the injection, patients may experience gastrointestinal discomfort, such as epigastric distention, pain, nausea, vomiting, etc. They may also experience neurological side effects such as headache, dizziness, deafness, tinnitus, etc. Those with serious symptoms should go to the hospital for treatment in a timely manner.