Pain Medicine Side Effects: Care Instructions

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When you go to a medical facility in pain, you may get a strong medicine called an opioid to give you relief. The medicine may be given in a vein (by IV) or as an injection (shot). Examples of opioids include fentanyl, hydromorphone, and morphine. While these medicines help relieve pain, they also have side effects.

For your safety, it's important that you know how this strong pain medicine affects you. Common side effects can include:

  • Constipation.
  • Nausea or vomiting.
  • Feeling dizzy or lightheaded.
  • Feeling sleepy.

The doctor has checked you carefully, but problems can develop later. If you notice any problems or new symptoms, get medical treatment right away.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

How can you care for yourself at home?


  • Don't do anything for 24 hours that requires attention to detail, such as going to work, making important decisions, or signing any legal documents. Strong pain medicines like opioids can make your mind foggy. It takes time for the effects to wear off completely.
  • Don't drive a car until you are sure the effects from the medicine are gone.


  • Be safe with medicines. Read and follow all instructions on the label.
    • If the doctor gave you a prescription medicine for pain, take it as prescribed.
    • If you are not taking a prescription pain medicine, ask your doctor if you can take an over-the-counter medicine.


  • You can eat your normal diet, unless your doctor gives you other instructions. If your stomach is upset, try clear liquids and bland, low-fat foods like plain toast or rice.
  • If your strong pain medicine makes you feel constipated, talk to your doctor about a laxative. If a laxative doesn't work, your doctor may suggest a prescription medicine.
  • Drink plenty of fluids (unless your doctor tells you not to).
  • Don't drink alcohol for 24 hours after taking opioids.

When should you call for help?

Call 911 anytime you think you may need emergency care. For example, call if:

  • You have trouble breathing.
  • You passed out (lost consciousness).

Call your doctor now or seek immediate medical care if:

  • You are having trouble urinating.
  • You are sleepy and confused.
  • You have new or worse pain.

Watch closely for changes in your health, and be sure to contact your doctor if:

  • You do not get better as expected.

The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.