COWS Score for Opiate Withdrawal

Introduction

The Clinical Opiate Withdrawal Scale (COWS) measures how severe a person’s opioid withdrawal is. It was published in 2003 by addiction medicine physicians Donald R. Wesson, MD, and Walter Ling, MD, of the UCLA Integrated Substance Abuse Programs. It’s clinician-administered: the clinician observes the patient and asks about symptoms, rather than the patient filling out a form. the National Institute on Drug Abuse (NIDA) describes it as a tool that can be used in both inpatient and outpatient settings to reproducibly rate common signs and symptoms of opiate withdrawal and monitor these symptoms over time. NIDA is a US federal research agency within the National Institutes of Health (NIH), under the Department of Health and Human Services.The summed score for the complete scale can be used to help clinicians determine the stage or severity of opiate withdrawal and assess the level of physical dependence on opioids. Its most common use is deciding when to start buprenorphine. Starting it too early, before withdrawal is underway, can trigger sudden, severe withdrawal (called precipitated withdrawal).

What it assesses

The clinician rates 11 signs and symptoms: resting pulse rate, sweating, restlessness, pupil size, bone or joint aches, runny nose or tearing, stomach upset, tremor, yawning, anxiety or irritability, and gooseflesh skin. Each item has its own score options, so the points don’t follow a simple 0–4 pattern. For example, the resting pulse is scored 0 pulse rate 80 or below; 1 pulse rate 81-100; 2 pulse rate 101-120; 4 pulse rate greater than 120, and stomach upset over the last half hour ranges from 0 no GI symptoms up to 5 multiple episodes of diarrhea or vomiting.

The clinician scores only what’s due to withdrawal. The official instructions say to rate on just the apparent relationship to opiate withdrawal. For example, if heart rate is increased because the patient was jogging just prior to assessment, the increase pulse rate would not add to the score. Likewise, for bone or joint aches, if patient was having pain previously, only the additional component attributed to opiates withdrawal is scored

How it’s scored

The 11 item scores are added for a total from 0 to 48. Higher scores mean more severe withdrawal.

How results are used

The COWS is usually repeated over hours to track whether withdrawal is getting worse or improving, and to judge response to treatment. For buprenorphine, many protocols wait until the score reaches at least the mild-to-moderate range, often around 8 to 12 or higher, before the first dose. Higher thresholds are sometimes used for people who have used fentanyl. These thresholds come from clinical protocols, not the original scale, and they vary between programs, so follow local protocol.

Limitations

The COWS measures how severe withdrawal looks at a given moment. It does not diagnose opioid use disorder, establish which opioid was used or when, prove tolerance, guarantee any medication decision, or rule precipitated withdrawal in or out. Some items, like anxiety and aches, rely on the patient’s report, and others can be affected by illness, other drugs, or stress. NIDA addresses concerns about objectivity, noting that the symptoms of opioid withdrawal have been likened to a severe influenza infection (e.g., nausea, vomiting, sweating, joint aches, agitation, tremor). Fentanyl has also made withdrawal timing less predictable, so scores should be read alongside a careful history. Always consider the possibility of comorbid withdrawal conditions from alcohol, benzodiazepine, or sedative-hypnotics, which may be life threatening alone or in combination.

Resources

• For more information on what is precipitated withdrawal and how to avoid it:

  • PDF Explanation (naabt.org)

  • The National Alliance of Advocates
    for Buprenorphine Treatment (naabt.org) website

• For more information and resources on substance abuse:

  • Substance Abuse and Mental Health Service Administration (SAMHSA) website

Wesson DR, Ling W. The Clinical Opiate Withdrawal Scale (COWS). J Psychoactive Drugs. 2003 Apr-Jun;35(2):253-9.

The National Alliance of Advocates for Buprenorphine Treatment COWS Flow sheet (2011).