Pain Medications

Based on "Essential Pain Pharmacology"
written by Howard S. Smith MD, Marco Pappagallo MD

Pain Medications

Pain medications, also known as analgesics, are a type of drugs used to relieve pain. They either stop pain signals from going to the brain or alter the brain’s interpretation of those signals. Analgesics prevent the brain from processing pain signals, yet do not rely on anesthesia or loss of consciousness to achieve their pain-killing effect.

Pain medications are used to treat pain related to many conditions, including the following:

  • arthritis and other types of joint pain
  • headaches
  • sore muscles, muscular aches
  • menstrual cramps
  • back pain (including herniated discs, degenerative disc disease and spinal stenosis)
  • trauma pain
  • childbirth pain
  • surgical pain
  • orofacial and dental pain
  • fibromyalgia
  • colds and flu

Pain medications are a quick and effective way of coping with mild to severe pain. While these drugs do not treat the cause of the pain, they can provide enough relief to make people more comfortable and to allow them to carry out their daily routines. Most analgesics take from 30 to 60 minutes to start working if taken in tablet form. Intravenous or injected pain relievers are often work much quicker.

Types of pain medications

There are two primary types of pain medications:

  • Non-narcotic pain medications, also known as non-opioids. These medications are milder forms of analgesics and include acetaminophen, the most commonly used over the counter non-narcotic analgesic. Other drugs are not technically part of the analgesic family, but are nonetheless considered analgesics in practice. These include nonsteroidal anti-inflammatory drugs (NSAIDs).
  • Narcotic pain medications, also known as opioids. These medications are stronger analgesics that are used when pain signals are too severe to be controlled by non-narcotic analgesics. Analgesics in this category include natural narcotics (derived from the opium poppy), such as morphine and codeine, and synthetic narcotics, such as propoxyphene (Darvon) and meperidine (Demerol).

Non-narcotic analgesics

Non-narcotic analgesics are milder forms of the painkillers that include acetaminophen. Acetaminophen is used to treat mild-to-moderate pain and reduce fever. Acetaminophen provides relief from pain by elevating the amount of pain you can tolerate before you experience the feeling of pain. The best known brand of acetaminophen is Tylenol, but there are also many generic versions available.

Nonsteroidal anti–inflammatory drugs (NSAIDs)

Nonsteroidal anti-inflammatory drugs (NSAIDs) are medications used to reduce pain and inflammation. These drugs are often the first choice for treating the pain and inflammation associated with conditions ranging from headaches to osteoarthritis. Some NSAIDs, such as aspirin, ibuprofen, and naproxen, are available over-the-counter.

NSAIDs are used to relieve pain related to the following conditions:

  • arthritis, osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, gout, pseudogout, psoriatic arthritis, juvenile arthritis
  • muscle sprains and strains
  • minor injuries and trauma pain
  • headaches, including tension headaches and migraines
  • some types of eye pain and ear pain
  • toothaches and other types of dental pain, orofacial pain
  • neck pain, including whiplash
  • back pain, including back sprain, degenerative disc disease, herniated disc, sciatica and spinal stenosis
  • shoulder pain
  • arm and wrist pain, including tennis elbow and carpal tunnel syndrome
  • menstrual cramps and other types of pelvic pain
  • leg pain, knee pain and foot pain
  • joint pain
  • chronic fatigue syndrome
  • complex regional pain syndrome
  • fibromyalgia

NSAIDs are usually not appropriate for people with stomach problems because they may have a higher risk for stomach bleeding. Most NSAIDs increase the risk of serious adverse cardiovascular events, such as heart attack or stroke.

Common side effects of NSAIDs include: upset stomach, nausea, abdominal pain, diarrhea, heartburn, unusual bleeding, drowsiness, dizziness, skin rashes. More severe side effects of NSAIDs include: allergic reactions, high blood pressure, stomach bleeding, stomach ulcers (with long-term use), kidney or liver problems.

COX-2 inhibitors

COX-2 (Cyclo-oxygenase-2) inhibitors are unique type of nonsteroidal anti-inflammatory drugs designed to relieve pain as effectively as other NSAIDs but to be less harmful to the gastric mucosa. Conditions treated with COX-2 inhibitors include osteoarthritis, rheumatoid arthritis and some types of acute pain.

COX-2 inhibitors differ from traditional NSAIDs by targeting selectivity for the pain-signaling prostaglandins. They do not affect cyclo-oxygenase 1 (COX-1), an enzyme protecting the stomach lining . Thus, COX-2 inhibitors relieve pain without causing stomach problems often associated with other NSAIDs.

Some COX-2 inhibitors (Vioxx and Bextra) have been withdrawn from the market by their manufacturers after being linked to an increased risk of serious side effects including heart attack, stroke and gastrointestinal bleeding. As a result, celecoxib (Celebrex) is the only remaining COX-2 inhibitor available in the United States.

Narcotic pain medications

Opioids (also called narcotics) are powerful medications often used to manage pain. These drugs include natural opiates (derived from the opium poppy plant) and synthetic narcotics. Narcotic pain medications are the most effective analgesics available today. Opioids act by attaching to specific proteins called opioid receptors. These receptors are located in the brain, spinal cord, and gastrointestinal tract. When these compounds attach to certain opioid receptors in the brain and spinal cord, they can effectively change the way a person perceives pain.

Although opioids are effective in providing pain relief, many physicians fail to prescribe them because they fear the patients may become addicted to the substances. However, research has shown that patients who properly use opioids under close supervision of a physician are extremely unlikely to become addicted to them.

Narcotic pain medications are usually prescribed to manage pain related conditions and procedures such as:

  • severe injury and trauma pain
  • severe musculoskeletal pain, such as back pain or neck pain
  • surgery
  • postpartum (after-labor) pain
  • severe dental pain

Opioids are also used to block pain during numerous medical and dental procedures and may be used just before or during an operation to help anesthesia work more effectively.

Some of the more common side effects include: drowsiness, constipation, itching, dizziness, lightheadedness, unclear thinking, nausea, vomiting, dry mouth, sedation, reduced sex drive, accelerated heart rate, depression of respiration and cough reflex, gastrointestinal disorders, decreased motor response rate, urinary retention. In high doses opioids can affect breathing and cause severe respiratory depression.


Tramadol is a centrally acting analgesic indicated for the management of moderate to moderately severe pain. It has properties similar to both opioids and antidepressants. Tramadol reduces pain by interfering with pain signals to the brain (like an opioid) and by affecting neurotransmitters (like an antidepressant).

Most common adverse reactions of tramadol are nausea, dizziness and vomiting. Respiratory depression and constipation are less common with tramadol and less pronounced than with other opioids. Compared to opioids, tramadol has a low risk of development of tolerance, physical dependence, or addiction. Tramadol has a low risk of abuse because it has only a weak opioid effect and its monoaminergic action could inhibit the development of dependence. Relatively low abuse potential of tramadol has been demonstrated by postmarketing surveillance data.

Other classes of drugs

Other classes of drugs that can be used to relieve pain include anticonvulsants, antidepressants and psychostimulants, marijuana-like cannabinoids, corticosteroids to reduce inflammation, disease-modifying antirheumatic drugs (DMARDs) to decrease damage to joints, and nerve blocks and other anesthetics.

Many antidepressants can relieve chronic pain in addition to relieving depression. These drugs also may improve sleep quality, which may in turn help reduce pain. In some cases, antidepressants work by treating accompanying depression that makes chronic pain more difficult to handle.

Tips and facts to know
  • Increasing the dosage of medication increases the risk of adverse effects or drug toxicity.
  • Combining several medications, puts you at risk of drug interactions.

Analgesics will not:

  • cure whatever is causing your pain
  • prevent a headache
  • boost your energy levels

The type, number of and intensity of negative effects will depend upon:

  • the type of analgesic being used
  • the number of analgesics consumed
  • how long the analgesics are being used for
  • the health of the user
  • existing medical conditions
  • whether other drugs are also being used
References & Resources

  • 1. The Merck Manual of Medical Information. Mark H. Beers et al., eds. 2nd Home Edition. Whitehouse Station, NJ: Merck; 2003.

Published: May 05, 2007
Last updated: May 05, 2017


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