Let's take a minute to talk about your medication. 

This is a hydromorphone injection, and it treats pain. When a dose is given as a shot under your skin or into your muscle, it starts working in 10 to 30 minutes. When a dose is given into your vein, or 'IV', it starts working in just a few minutes. 

Some common side effects can occur. You could feel tired, so wait until you know how it affects you before doing activities that require you to be alert, like driving. You might feel dizzy. To reduce this, you should stand up slowly after sitting or lying down. Some patients have a dry mouth, sweating, flushing or itching. It can also cause nausea and constipation, and you should ask your doctor or pharmacist how to prevent these. If these or other side effects become reasons you want to stop taking this medicine, please talk to your doctor or pharmacist. 

This medicine can become habit-forming with regular use. So, don't suddenly stop taking it unless your doctor says it's okay. 

As with any medicine, rare but more serious side effects can occur. Get emergency help if you have unusual changes to your body, like problems breathing, extreme sleepiness, fainting, stomach pain or swelling in your face or mouth. 

You should always check with your doctor or pharmacist before taking other medicines. Also, you should not drink alcohol. 

Hydromorphone can be dangerous to others. If you have doses at home, store them securely. Also, discard any unused doses promptly. Your pharmacist can advise you on how to dispose of them in your area. 

Women should talk to their doctors before becoming pregnant or breastfeeding. 

For best results with hydromorphone, work with your doctor to find the lowest dose that best controls your pain.