Enkephalins (Met-Enkephalin, Leu-Enkephalin)

Opioid agonists can suppress respiratory drive, particularly at higher doses or with repeated administration. Monitor respiratory rate and oxygen saturation. Seek immediate medical attention if breathing becomes shallow or labored. Risk increases with concurrent CNS depressants.

Opioid-induced nausea occurs in 20-30% of users, often resolving within days as tolerance develops. Take with food or ginger supplements. Antiemetics (ondansetron) may be used if severe.

Opioids reduce GI motility. Increase fluid intake, dietary fiber, and physical activity. Stool softeners or osmotic laxatives (polyethylene glycol) are effective preventive measures.

Opioids can cause orthostatic hypotension and CNS effects. Rise slowly from sitting or lying positions. Avoid driving or operating machinery until effects are understood.

Opioid-induced itching is mediated by mast cell degranulation and histamine release. Antihistamines (cetirizine, diphenhydramine) or low-dose naloxone may provide relief.

Opioid effects on mood are variable and dose-dependent. Some users experience mild euphoria; others may experience dysphoria or emotional blunting. Monitor mood changes and report significant changes to a healthcare provider.

Repeated opioid exposure leads to receptor desensitization and reduced efficacy. Tolerance typically develops over days to weeks. Dose escalation may be necessary, but increases risk of adverse effects and dependence.

Chronic opioid use can produce physical dependence, characterized by withdrawal symptoms (anxiety, insomnia, muscle aches, sweating) upon discontinuation. Taper gradually under medical supervision to minimize withdrawal.

Opioid agonists cause pupil constriction. This is a characteristic sign of opioid activity and is generally benign but may affect vision in low-light conditions.

Redness, swelling, or mild discomfort at the injection site. Rotate injection sites to minimize risk. Apply ice if needed. Severe or persistent reactions warrant medical evaluation.

Opioids can trigger or worsen headaches in some users. Ensure adequate hydration and consider over-the-counter analgesics if needed.

Opioid-induced seizures are rare but documented, particularly at high doses or in susceptible individuals. Seek immediate medical attention if seizure activity occurs. Avoid in patients with seizure history without medical supervision.