 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  also be used to help you feel sleepy/relaxed before and after surgery, during other procedures, or during labor and delivery. It may also be used to help certain opioid pain relievers (such as meperidine) work better.Promethazine is an antihistamine and works by blocking a certain natural substance (histamine) that your body makes during an allergic reaction. Its other effects (such as anti-nausea, calming, pain relief) may work by affecting other natural substances (such as acetylcholine) and by acting directly on certain parts of the brain.This drug is not approved for use in children younger than 2 years due to an increased risk of side effects (such as slow/shallow breathing). See also Warning section. How to use Phenergan Vial See also Warning section. It is best to inject this medication deep into a muscle. It may also be given by injection slowly into a large vein by a health care professional. Do not inject this medication under the skin or into an artery. For nausea and vomiting, use this medication as directed by your doctor, usually every 4 hours as needed. If you have any questions about the proper use of this medication, ask your doctor or pharmacist. If you are </s>