Pain Assessment

Timing and Frequency of Screening for and Assessment of Pain

All clients should be screened for the presence of pain. If pain is present, then you should assess the pain.

Timing and frequency of screening for and assessment of pain depends on several factors. It can be useful to check with the unit/institution where you work about pain assessment frequency. You should perform routine screening for and assessment of pain at specific times and during certain situations such as:

  • Admission to a healthcare setting.
  • Primary healthcare visit. 
  • Start of shift when first assessing a client.
  • Change in the client’s condition (e.g., change in vital signs) or other potential physiological or behavioural signs of pain. Oftentimes, pain is assessed with each set of vital signs.
  • Prior to a procedure or activity to establish a (e.g., walking for the first time postoperatively) as well as during and after a procedure or activity. 
  • After treatment (e.g., after the provision of pain medication such as ) and continued reassessment until treatment takes effect. Reassessment is often based on the medication’s onset of action (how long the medication takes to begin taking effect), peak effectiveness (how long it takes for the medication to be at its maximum concentration in the body, thus its greatest therapeutic effect) and duration (length of time that a medication produces a therapeutic effect) (Chippewa Valley Technical College, n.d.). Continued reassessment of pain may be needed so that you can determine whether additional treatment is required.
  • When there is a written order for pain assessment. For example, physicians and nurse practitioners sometimes provide written orders for pain assessments (e.g., pain assessment every four hours or pain assessment every eight hours).

Pain assessments are often repeated to evaluate the effectiveness of treatment and medication. First, you should assess the client’s baseline and review the client’s chart to get a full picture of the client’s pain. The timing of repeat pain assessments will depend on several factors (see Table 2). Always compare your findings to the client’s baseline.

Table 2: Pain reassessment.






Time for the medication to take effect.


Some over-the-counter oral pain medications can start taking effect in 15–30 minutes, but peak effectiveness usually takes one hour and up to two hours. Typically, pain is reassessed between 30–60 minutes after oral medication is given.

Intravenous quick acting opioid pain relievers (e.g., morphine) can take effect within 1–2 minutes with peak effects between 5–15 minutes. Opioids may have even quicker peak effects, e.g., 2–5 minutes for fentanyl (Vahedi et al., 2019).


Specific situation


In acute situations where you are attempting to control the pain quickly with an intravenous medication, you may reassess within 2–5 minutes. Additionally, you should assess for adverse effects such as respiratory depression with opioid administration. Do not assume that a client is not in pain because their eyes are closed, or because they are smiling or talking.

In other situations, a client may be given an oral pain medication at bedtime; thus, you may not reassess until they wake up or in the morning. You might ask the client to ring their call bell if the pain has not subsided in an hour.


Contextualizing Inclusivity

Consider forms of pain management other than traditional Western medications when making decisions regarding pain reassessment. For example, cannabis is now legal in Canada, and prescription of medical cannabis has become more common, particularly for cancer pain and neurological conditions such as multiple sclerosis (Health Canada, 2016). Cannabis may be taken alone or in conjunction with other medications and can be taken through inhalation or oral ingestion (foods/oils/capsules). Based on the onset of action (Health Canada, 2016), reassessment may be appropriate within 15 minutes, or within 30 minutes with oral ingestion. As a nurse, you will need to assess the many other forms of pain management that a client may choose to use (e.g., mindfulness meditation, acupuncture, play for children) and assess effectiveness as needed.

An open-ended and inclusive question to ask clients is: Tell me about the ways you manage your pain?

Some Indigenous clients may choose to utilize traditional medicines instead of, or along with, Western medications. To learn more about treating Indigenous clients using traditional medicines, see Pain, Pain Killers and Indigenous Peoples: Choose the right medicine for you in partnership with your physician.

Activity: Check Your Understanding


Chippewa Valley Technical College (n.d.). Nursing pharmacology.

Health Canada (2016). Consumer information – Cannabis (Marihuana, marijuana).

Vahedi, H., Hajebi, H., Vahidi, E., Nejati, A., & Saeedi, M. (2019). Comparison between intravenous morphine versus fentanyl in acute pain relief in drug abusers with acute limb traumatic injury. World J Emerg Med, 10(1), 27-32.


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