The hard lump left by the buttock injection is generally not very harmful, often related to the drug, needle stimulation; may also push the speed of the drug is relatively fast, the muscle has not been completely absorbed caused by the majority of this time do not need to carry out special treatment. As the drug is gradually absorbed, after a period of time they can recover, usually there is no danger. Buttock injection belongs to a kind of intramuscular injection, due to the buttock muscle is more abundant, and there is no important tissues and organs in the buttock, the safety is also higher. However, in the process of injection, due to the drug, needle stimulation, may lead to local scarring, edema; may also be pushed into the speed of the drug is relatively fast, the muscle has not been completely absorbed caused by the appearance of the visible buttocks have hard lumps. In the process of scar healing, the hard lump will gradually decrease or disappear. For patients who need long-term intramuscular injections in the buttocks, it is recommended that the patient alternates between left and right side injections, and after the injection is completed, local hot compresses can be applied to promote blood circulation and reduce local swelling. If the hard lump is combined with redness, swelling and pain, it suggests that there may be bacterial infection, and anti-inflammatory treatment can be carried out under the guidance of a professional physician; if it is caused by simple muscle hardness, magnesium sulfate powder can be used for wet compresses as prescribed by the doctor, once a day in the morning and once in the evening, which can help to reduce the swelling and dissipate the knots. In addition, in the intramuscular injection must be standardized operation, often change the site, such as discomfort, please consult a doctor immediately.