Defining Opioid Tolerance | What Tolerance Means For Addiction & Pain Management

Opioid analgesics are prescription medications used to treat severe pain, chronic pain, and cancer pain. Although opioids are effective for treating pain, some people may develop a tolerance after chronic opioid use. 

Opioid-tolerant patients often require higher doses to adequately relieve pain. Tolerance may also increase the risk of dependence and addiction. Open communication with your doctor about your concerns regarding tolerance and addiction can help them determine the best care for you. 

Opioid Therapy, Dosage, & Tolerance

Opioid agonists are a class of drugs that activate opioid receptors in the central nervous system (CNS). Activation of these receptors reduces the number of pain messages being sent in the brain. 

Opiates are typically not the first choice for treating pain because of the risk of dependence and addiction. Opioid therapy is usually initiated only for severe pain or if other methods of pain relief are ineffective. 

Opioid therapy may include the following medications:

• oxycodone
• morphine 
• fentanyl
• hydromorphone

Dosing is usually adjusted to the lowest amount possible that treats pain without adverse effects. However, repeated use may lead to the desensitization of opioid receptors. This means you may need higher doses to achieve the same effects.

Opioid Tolerance 

Tolerance may be influenced by changes in opioid receptor neurons (nerve cells) or changes in how cells interact. It is also believed that long-term opioid use may play a role in the development of tolerance.

Once a person becomes tolerant, a doctor may increase the dose to manage pain. Unfortunately, tolerance can lead to an endless cycle of increasingly higher doses of opioids. 

High doses of opioids also increase the risk of experiencing side-effects, including:

• constipation
• nausea
• vomiting
• itchiness
• respiratory depression 

Dependence & Addiction

As tolerance increases, higher doses can lead to physical dependency. Physical dependence means you may experience opioid withdrawal symptoms if you suddenly stop taking the medication.  

Tolerance is also associated with opioid use disorder (OUD), or opioid addiction, in some people. Opioid dependence and addiction may require professional treatment, including detox, drug rehab, and medication-assisted treatment. 

Medication-Assisted Treatment (MAT) 

A common and effective treatment for opioid addiction is MAT, which includes the FDA-approved opioid drugs methadone and buprenorphine. 

Methadone reduces cravings for up to 24 hours but may only relieve pain for up to 8 hours. A person on methadone maintenance may require short-term use of additional opioids, like oxycodone, to treat acute pain. 

Buprenorphine is a powerful opioid but it has a ceiling effect. This means that after a specific dose, it will stop increasing its analgesic effects. 

Doctors may prefer to gradually taper buprenorphine before a surgery for post-operative pain control. This allows health care professionals to administer other opioids that may be more effective in treating pain.

Opioid-Induced Hyperalgesia 

Opioid-induced hyperalgesia (OIH) is often confused with opioid tolerance but the two may occur simultaneously. OIH is a condition that causes increased sensitivity to pain in people who take opioid medications. 

Signs of OIH may include:

• original pain may increase or affect a wider area
• new pain may develop in other areas of the body
• increased sensitivity to pain

To control pain in people with OIH and increased tolerance, clinicians may gradually taper the opioid prescription. Tapering means the opioid dose is slowly decreased until it is eventually discontinued. 

In place of opioids, your doctor may choose to continue your pain management therapy with non-opioid medications. 

Non-Opioid Pain Management 

Non-opioid pain management medications may include:

• Tylenol 
• Advil 
• Lyrica 
• ketamine
• lidocaine
• clonidine, which can be effective in easing withdrawal symptoms

Low-dose ketamine infusions have been proven effective in opioid-tolerant individuals. Ketamine can produce pain relief and sedation without the respiratory depression associated with opioids. 

In opioid-naive patients (new patients) or in high doses, opioid administration can cause respiratory depression. Respiratory depression is the primary cause of opioid overdoses and is characterized by slow and labored breathing.

If you or a loved one is seeking more information about addiction treatment programs, please contact Ark Behavioral Health today.