FAST FACTS: Opioid Side Effects (Adverse Effects)


Side effects of common medication pain treatments can limit good pain control, especially in older adults who are physically vulnerable.


General Information:

  • Older adults are more sensitive to side effects of medications
  • Side effects should be anticipated when using pain medications
  • Watch for dry mouth, constipation, excessive drowsiness, nausea, disorientation, lack of urine output, or a decline in breathing in and out
  • Work with your family member’s healthcare provider to prevent and vigorously treat these side effects
  • Opioids, which are prescription pain medications used for the treatment of moderate to severe pain, should start at a low dose and be slowly increased to minimize harmful side effects
  • A routine laxative should be prescribed when opioid treatment is started. Laxative doses should increase when the opioid dose is increased.
  • Tolerance is the body's normal response to continued exposure to a medication resulting in a reduction of the side effect over time. This applies to most opioid side effects, except constipation
  • If side effects last for a long time, speak with your family member’s healthcare team to discuss treatment options

Overview of Common Adverse Effects to Opioid Pain Medication:

  • Drowsiness and change in cognition (thought, understanding, awareness)
    • This generally improves within 72 hours of starting or increasing an opioid medication
  • If drowsiness or decrease in cognitive function persists, report this to your family member’s healthcare provider who will review the situation.
  • Decline in breathing in and out
    • Common fear, but actually very rare when opioids are used for routine persistent pain.  Note: changes in respiration at end of life are to be anticipated.
  • Disorientation
    • Report to this to your family member’s healthcare provider to determine cause
  • Nausea
    • Generally resolves within 72 hours of initiating a new pain medication
    • Non-drug treatments include:
      • Lie down
      • Take medication with food
      • Increase circulating air
      • Place a cool towel on head/neck
      • Do not eat foods at extreme temperatures
      • Avoid spices in foods
      • Avoid strong odors
  • Constipation
    • The healthcare provider should prescribe medication to combat constipation along with opioid pain medications
    • Take medications for constipation as prescribed
    • If constipation persists, report to the healthcare provider, who will increase dose as needed
  • Involuntary muscle twitching
    • Can occur with high doses of opioid therapy
    • Report to the healthcare provider
  • Itching
    • Can occur with high-does opioid therapy
    • This is most common with morphine but can occur with other opioids.  For most people, itching is a side effect, not an allergy.
    • Report to the healthcare provider
    • Antihistamines are a common medication used for itching
    • Your family member may also benefit from cool compresses and/or moisturizers to sooth the itching

  • What Else You Should Do
    • Report all information about adverse effects to their healthcare provider
    • Encourage your family member to use a Pain Diary to note important information (such as side effects) useful to the provider


  1. Used with permission of K. Herr, PI, Cancer Pain in Elders: Promoting EBP's in Hospices; NCI Grant R01CA115363; Adapted from AHRQ Grant RO1 HS 10482; M. Titler; PI; Revised 2/7/07.
  2. Reuben DB, Herr KA, Pacala JT, et al. Geriatrics At Your Fingertips: 2021, 23rd Edition. New York: The American Geriatrics Society; 2021.

Revised January 2022

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