Nalox 400mcg Injection is an opioid antagonist. It is used for the treatment of opioid toxicity. It helps to reverse the depressant effect on breathing, and on other parts of the body. It also helps to determine if a patient has taken an overdose of opioids. Nalox 400mcg Injection is given as an injection into veins, muscle, or under the skin by a doctor or nurse. It is advisable not to self-administer the injection. Your doctor or nurse will train your family member or caregiver about how to inject the medicine in case of an emergency. It is advisable to follow your doctor's advice while being on the treatment. The most common side effects of this medicine include injection site redness, dizziness, headache and increased or decreased blood pressure. Most of these usually go away within a short time of the injection. If you are bothered by them or they go on for longer, talk to your doctor or nurse. You should not drive if this medicine makes you feel dizzy. Before taking it, tell your doctor if you have heart problems, high blood pressure, or high heart rate. This may affect your treatment. Pregnant or breastfeeding women should consult their doctor before taking this medicine. Some other medicines you are taking may interfere with it, so make sure your doctor knows about all the other medicines you are using.