Opioids Tolerance (to Pain Meds): Signs, Causes, Effects

Opioids tolerance isn’t the same as dependence or addiction. Learn what it is and how it affects you when you take prescription painkillers.

Opioids tolerance is a legitimate concern of people taking prescription painkillers. Tolerance means that the body and brain get used to the amount of opioids in the system. Because the body and brain adapt to the presence of these drugs, someone taking prescription opioids needs more painkillers to provide the same amount of relief.

Tolerance is not the same thing as opioids dependence or addiction. If someone has developed dependence, he will experience opioids withdrawal symptoms when he stops taking the opioid drug. Addiction is a disease involving the brain and means that someone can no longer control opioid use.

If you need more of your opioid painkiller to dull your pain to the same level as you were getting with a lower dose, you might have developed a tolerance of opioids. It doesn’t come from lack of control or compulsive use, so how does tolerance develop?

How Tolerance of Opioid Pain Medication Develops

Opioid mechanism of action makes it is fairly easy to become tolerant of painkillers, even when you’re following your doctor’s instructions for how to take them. The predictable pattern of tolerance development is often referred to as the tolerance trajectory.

The trajectory, or path, that opioid use takes is this: Someone begins taking opioids for pain as prescribed. Eventually, that dose isn’t as effective, and she needs more. The doctor increases the dose, and it works until it doesn’t. The pattern of increasing doses just to maintain the same level of pain relief happens because tolerance has developed.

Tolerance develops in different ways:

  • At the cellular level when opioids bind to opiate receptors, enzymes are released that fire chemicals in the cell. Eventually, the enzymes adapt to the opioid and cease to react. Now more painkillers are needed in order to trigger pain-relieving reactions.
  • Body systems themselves experience changes. For example, brain chemistry grows accustomed to the painkillers and thus needs more to spring into pain-relieving action.
  • In response to prolonged opioid presence, the body changes the way it metabolizes the painkillers. This leads to a reduced opioid concentration in the blood, and more are needed to compensate.
  • Sometimes learned tolerance is at work. Someone taking opioid painkillers learns to function well with the levels of opioids in his system. His functioning has adapted, but the pain is still there, so he needs a greater amount of opioids.

You won’t notice the inner workings of tolerance development, but you’ll recognize tolerance if you no longer feel the effects of the painkiller and instead feel more pain. As a result, you’ll find yourself needing to take opioids more frequently or take a stronger dose. A doctor has to prescribe the increase, so if you do need to see a doctor for this reason, it would be a good opportunity to discuss the possibility of opioids tolerance with him.

Effects and Dangers of Opioids Tolerance

A tolerance of opioids can have serious negative consequences. It increases the risk of dependence, addiction, and opioid overdose. Overdose is a particular risk because with opioids, it can happen fairly easily and unintentionally as the levels in the system increase.

Opioid tolerance has another negative effect that affects future pain and the need for pain medication. Tolerance doesn’t fully disappear. It lasts into the future even when medications are stopped.

Therefore, if you need prescription painkillers down the road, you’ll have to start at a higher dose than you’d otherwise need because your system is still accustomed to a certain level of opioids. Further, chances are high that you’ll “max out” on prescription painkillers. Tolerance will develop with each new dose until it’s unsafe to take higher or more frequent doses. If that happens, pain won’t be completely relieved.

Opioid Tolerance Help. Is Opioid Tolerance Reversal Possible?

So far, drug replacement therapies don’t work for opioid tolerance. While using an opioid antagonist like methadone can help with addiction, it doesn’t help to reverse tolerance.

That said, researchers are working on developing a drug replacement therapy that does work. Additionally, many are hopeful that adding a very low dose of an opioid antagonist called naltrexone with oxycodone (the combination is known as Oxytrex) will help oxycodone work longer. This doesn’t reverse tolerance, but it seems to prolong its development.

Even though opioid tolerance can’t be fully reversed, there are ways to deal with it once it happens.

  • Stop taking opioid painkillers (done gradually and often with help).
  • Give your brain and body time to heal and recover.
  • Seek alternate methods of pain relief, such as going to interdisciplinary chronic pain programs, working with a physical therapist or personal trainer (many specialize in movement for pain management), or attending support groups for people living with chronic pain.

Developing a tolerance to opioid pain meds is undesirable, but it doesn’t mean that you are addicted to drugs, and it doesn’t mean you can’t take other measures to manage your pain.

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Last Updated: 01 June 2018

Reviewed by Harry Croft, MD

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