In brief
- Do not stop or reduce opioids on your own. Any change in an opioid regimen should be planned, gradual, and supervised.
- An opioid does not repair a disc, shrink a bone spur, restore cartilage, heal a tendon, or decompress a nerve root.
- With daily use the dose climbs, the pain does not improve, function does not improve, and every risk rises with each increase.
- Physical dependence is universal with daily use. Expected, not a character flaw.
This guide explains what these drugs do to the nervous system over time, and why long-term daily use is not recommended for chronic non-cancer pain.
If you are currently taking opioids
Do not stop or reduce them on your own. Abrupt discontinuation after sustained use causes withdrawal and can be genuinely dangerous. Any change in an opioid regimen should be planned, gradual, and supervised. Bring this guide to your next visit and we will discuss your specific situation.
How opioids act on the nervous system
- They bind a specific receptor. Opioids attach to mu-opioid receptors on nerve cells in the spinal cord, brainstem, and brain, quieting transmission of the pain signal as it travels toward and within the brain.
- They do not treat the source of the pain. An opioid does not repair a disc, shrink a bone spur, restore cartilage, heal a tendon, or decompress a nerve root. The tissue problem generating the signal is unchanged; only the perception of it is altered.
- The same receptor drives reward. Mu receptors in the brain's midbrain reward circuit release dopamine. This is why opioids produce relief, calm, and sometimes euphoria, and why the brain reorganizes itself around the drug in a way that ibuprofen, gabapentin, or a nerve block never do.
What repeated daily use does
A nervous system exposed to a drug every day does not stay the same. Three predictable changes occur, and they compound one another.
- 1
Tolerance
Receptors are chemically tagged, pulled inside the cell, and become less responsive. The same dose produces less relief. Relief returns only by raising the dose, which restarts the cycle at a higher level of risk.
- 2
Physical dependence
Nerve cells counteract the drug by ramping up opposing internal signals, so the nervous system now requires the opioid simply to feel normal. This develops in essentially everyone taking daily opioids beyond a few weeks. It is not the same as addiction, but it does mean the medication cannot be stopped abruptly without withdrawal.
- 3
Opioid-induced hyperalgesia
With sustained exposure, immune (glial) cells in the spinal cord activate, NMDA receptors are recruited, and the brainstem begins to amplify rather than dampen incoming signals. The nervous system becomes more sensitive to pain, not less. Pain becomes more widespread, more diffuse, and less clearly tied to the original injury.
The dose climbs, the pain does not improve, function does not improve, and every risk listed below rises with each increase.
Why acute pain and chronic pain are not the same problem
Acute pain is an alarm
Chronic pain is a sensitized alarm system
Opioids make that specific problem worse. They act on the very system that has become sensitized and, through tolerance and hyperalgesia, sensitize it further. This is why a drug that works well for three days after surgery works against you at three years.
What the research actually shows
- Head-to-head trial (2018, 12 months). Patients with chronic back, hip, or knee pain were randomized to opioids versus non-opioid medications. Function was no better with opioids, pain intensity was slightly worse, and side effects were significantly more common.
- Pooled analysis of 96 trials, about 26,000 patients. Average pain improvement versus placebo was less than one point on a ten-point scale, below what most patients perceive as meaningful, and no better than anti-inflammatories or certain antidepressants.
- New-onset back and neck pain (2023). Opioids were no better than placebo at six weeks, and the group given opioids reported worse pain at one year along with higher rates of medication misuse.
Known risks and side effects by body system
| Body system | What happens | What it means for you |
|---|---|---|
| Breathing and overdose | Mu receptors in the brainstem blunt the reflex that makes you breathe when carbon dioxide rises. | This risk is dose-dependent and climbs sharply at higher daily doses. A large minority of long-term users develop central sleep apnea, in which the brain pauses breathing during sleep, and it is often silent. |
| Overall survival | Patients treated with long-term opioids for chronic non-cancer pain have a higher all-cause death rate than comparable patients treated with non-opioid medications. | Critically, the excess deaths are not only overdoses; cardiovascular and respiratory deaths are also increased. |
| Hormones | Opioids suppress the hypothalamic signal that drives the sex hormone axis, lowering testosterone and estrogen. This is common with long-term use. | Fatigue, low libido, erectile dysfunction, infertility, irregular or absent periods, low mood, muscle loss, and loss of bone density. A subset develop low cortisol (adrenal suppression): fatigue, low blood pressure, and a poor response to physical stress or illness. |
| Bones, balance, and falls | Sedation and dizziness combined with hormone-driven bone loss roughly doubles fracture risk in older adults. | Risk is highest in the first two weeks after starting a new opioid or increasing a dose. A hip fracture in an older adult carries substantial one-year mortality; this is not a minor side effect. |
| Digestive system | Opioid receptors line the gut wall. Motility slows and constipation affects the majority of long-term users. | Unlike pain relief, constipation does not fade with time; the gut never develops tolerance to it. It can progress to impaction and bowel obstruction. In some patients, escalating doses produce paradoxical worsening abdominal pain (narcotic bowel syndrome). |
| Immune function | Immune cells carry opioid receptors. Long-term exposure suppresses natural killer cell activity and lymphocyte function. | Long-term opioid use is associated with a measurably higher risk of pneumonia and serious invasive infection. |
| Brain, mood, and sleep | Impaired attention, short-term memory, and reaction time. Opioids suppress deep and REM sleep. | Driving is measurably impaired, especially in the first weeks and after any dose change. Risk of new-onset depression rises with both dose and duration of use. Poor sleep independently lowers the pain threshold, feeding the cycle. |
| Also commonly seen | Nausea, itching, sweating, ankle swelling, and urinary retention. Dry mouth leading to rapid dental decay. | Methadone can prolong the heart's electrical cycle (QT interval) and trigger dangerous rhythms. |
Combinations
Combinations multiply the breathing risk. Benzodiazepines (Xanax, Ativan, Valium, Klonopin), sleep medications, muscle relaxants, gabapentin or pregabalin, and alcohol each suppress breathing through separate pathways. Taking an opioid with a benzodiazepine multiplies the risk of fatal overdose several-fold, which is why this combination carries an FDA boxed warning.
Dependence, misuse, and opioid use disorder
- Physical dependence is universal with daily use. Expected, not a character flaw.
- Among patients on long-term opioid therapy, roughly one in four misuse the medication at some point, and approximately 8 to 12 percent develop opioid use disorder, which is true addiction.
- This is not predicted by willpower or character. It is driven by dose, duration of exposure, genetics, personal or family history of substance use, and untreated depression or anxiety. Every patient on long-term opioids carries some measure of this risk.
Any change to an opioid regimen should be planned, gradual, and supervised. Bring this guide to your next visit, or call or text 325-326-3433, and we will discuss your specific situation.
Patient education material from Abilene Pain. This guide is general information and does not replace the individual treatment plan discussed with your provider. Your care team: Nicolas Pugh, MD · Adrianne Anders, NP · Ted Chaka, PA.