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Pain Medications (cont.)

Medical Editor:

What are the side effects of pain medications?

All NSAIDS come with the risk of gastrointestinal ulceration and bleeding. A newer class of anti-inflammatories, the Cox-2 inhibitors, was developed to reduce this risk. It did not, though, eliminate it. In fact, another major issue emerged with these drugs: the possibility of severe and deadly vascular problems with long-term use, including heart attack and stroke. Two Cox-2 inhibitors, rofecoxib (Vioxx) and valdecoxib (Bextra), were withdrawn from the market because of this. Celecoxib (Celebrex) is still available. To minimize the risk of gastrointestinal issues, doctors will sometimes prescribe "protectant"drugs along with anti-inflammatories. These include such medications as misoprostol (Cytotec) and sucralfate (Carafate) as well as various acid-reducing compounds.

Most users of acetaminophen experience few, if any, side effects. But the drug can cause liver damage, especially when taking too much or if taken with alcohol. Because acetaminophen is present in many medications, from cold medicines and over-the-counter pain relievers to prescription drugs such as Percocet and Vicodin, users may not realize they are taking too much.

Opioid analgesics cause numerous side effects, including drowsiness, dizziness, respiratory depression, constipation, and urinary retention. Some of these effects will disappear with continued use or may be managed with other medications (constipation). Others, including urinary retention, may not. In addition, opioid use may lead to addiction or dependence, and patients often develop a tolerance to the drugs' analgesic effects. Upon withdrawal, dependent patients may experience a host of unpleasant side effects, including shivering and diarrhea.

Other side effects of opioid analgesics include:

Mixed opioid agonist-antagonists (pentazocine (Talwin Nx, Talacen, Talwin Compound), butorphanol (Stadol), nalbuphine (Nubain), dezocine) should not be used with pure opioid agonists (such as codeine (Codeine Sulfate), morphine (Avinza, DepoDur, Duramorph), oxycodone (Combunox, Endocet, Percocet, Percodan, Roxicodone). Doing so may trigger a withdrawal reaction.

The narcotic analgesic meperidine (Demerol, Mepergan) may be a poor choice for pain relief, particularly in patients with abnormal kidney function. It is linked to side effects including seizures.

Another opioid, propoxyphene, while a popular choice for pain relief, may have little effect in some patients.

The main side effect of muscle relaxants is drowsiness. This may be how they work to "relieve"pain. In addition, carisoprodol (Soma) use may lead to dependence because in the body it is converted into a drug similar to barbiturates; cyclobenzaprine (Flexeril) can cause dry mouth, constipation, confusion, and loss of balance; methocarbamol (Robaxin) discolors the urine to green, brown, or black; both metaxalone (Skelaxin) and chlorzoxazone (Parafon Forte, DSC) should be used with caution in those with liver problems.

Anti-anxiety drugs also carry the risk of sedation, particularly if combined with certain other medications (such as opioid analgesics) or alcohol. Other possible side effects include psychological changes, headache, nausea, visual problems, restlessness, and nightmares. Chest pain and heart pounding are also possible.

Some of the antidepressants used for pain relief are the older tricyclics. These come with numerous side effects classified as anticholinergic, including dry mouth, difficulty urinating, blurred vision, and constipation. Other possible side effects include lower blood pressure, fast heartbeat, palpitations, weight gain, and fatigue.

A few of the newer antidepressants also reduce pain -- and with less risk of anticholinergic issues. Still, the serotonin norepinephrine reuptake inhibitors (SNRIs) may cause the following common side effects:

  • Anorexia
  • Asthenia
  • Constipation
  • Dizziness
  • Dry mouth
  • Ejaculatory difficulties
  • Headache
  • Insomnia
  • Nausea
  • Nervousness
  • Sweating

Side effects associated with the anticonvulsants used for pain management commonly disappear over time. They include dizziness, drowsiness, and swelling of the lower extremities.

In general, short-term and/or low-dose corticosteroid use results in few side effects. But taking corticosteroids long-term can result in severe side effects, including:

  • Adrenal insufficiency -- a condition in which the body cannot adequately respond to physical stress
  • Atherosclerosis
  • Bone death
  • Cataracts and glaucoma
  • Elevated blood pressure
  • Elevated blood sugar
  • Fluid retention
  • Gastrointestinal bleeding
  • Mood changes
  • Osteoporosis
  • Suppression of the immune system
  • Trouble sleeping
  • Weight gain
  • Damage to local tissues

Chronic Pain/Back Pain

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