The Common Classification of Painkillers

The main objective of painkillers is to relieve pain and they're definitely useful for many different types of pain
The Common Classification of Painkillers
Nelton Abdon Ramos Rojas

Written and verified by the doctor Nelton Abdon Ramos Rojas.

Last update: 27 May, 2022

The word analgesia means “denial or lack of pain.” Hence, the overall classification of painkillers is also analgesic medication.”

According to the International Association for the Study of Pain (IASP), pain is an “unpleasant sensory and emotional experience.” This association of the pain experience usually has to do with real or potential injury.

There are two types of pain: acute and chronic. They differ in terms of sensory experience and also in terms of the emotional experience they imply. Thus, they require a different classification of painkillers.

Acute pain comes from a tissue injury and disappears after a wound heals. Overall, it’s difficult to find a specific tissue injury that involves chronic pain. Chronic pain, on the other hand, lasts a long time. Two examples of chronic pain are migraines and osteoarthritis.

As we indicated before, the emotional component is different in acute and chronic pain.

Often, these emotional symptoms can also be treated.

The Classification of Painkillers: Primary Analgesic Medications

The main objective of painkillers is to relieve pain and they’re definitely useful for many different types of pain. Since there are different types of pain, the classification of painkillers breaks down in three major groups.

Anti-fever Pure Analgesics

A person selecting medication.

Painkilling medications also have other functions. Even though the vast majority are also antipyretic (anti-fever) and anti-inflammatory, this group is the exception.

An example of a anti-fever pure analgesic is paracetamol. Thus, it doesn’t decrease inflammation, only lowers fever and reduces pain.

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)

NSAIDs owe their function to the blockade they make on the enzyme cyclooxygenase (COX). Furthermore, these drugs prevent COX from synthesizing the substances related to the inflammatory process, thus stopping it. Examples of NSAIDs are acetylsalicylic acid (aspirin) and ibuprofen .

However, there are different types of COX, each with a function, and there are also analgesic drugs that block each type specifically. These medications are called selective COX inhibitors (selective iCOX). Examples of them are celecoxib and rofecoxib.


Opioid analgesic drugs activate opioid receptors. In general, when an opioid receptor is activated, it hinders nerve transmission. Thus, an activated opioid receptor decreases nerve transmission of pain.

There are different types of opioids depending on their efficiency and other characteristics. Here, we find:

  • Pure agonists: These are the most effective and their best examples are morphine, codeine, and methadone.
  • Partial agonists are somewhat less effective. One example is Buprenorphine.
  • Agonist-antagonists: These activate certain opioid receptors and block others. Their best example is pentazocine.
  • Mixed: These have different functions than most opioids. One example is tramadol.

Note that opioids often produce undesired effects such as nausea, constipation or sedation.

Discover: Treat Fibromyalgia Naturally with These Herbs

Classification of Painkillers: Secondary Analgesic Medications

The primary goal of secondary painkillers is not necessarily to relieve pain. In fact, they were, in fact, invented to alleviate other conditions. Still, they do relieve some type of specific pain.


As we’ve already explained, it’s common to associate depressive symptoms with pain, especially chronic pain. Antidepressants can be beneficial in this regard. One of the most used is amitriptyline.


Antiepileptics reduce nerve transmission. When using them, the nerve transmission of pain decreases. Carbamazepine and lamotrigine are the most common.

Muscle Relaxers

Muscle relaxers can relieve muscle pain. If the origin of the pain is muscular, these medications relax the affected muscles and decrease the pain. In addition, they can help resolve the injury in these cases.

Overall, the most common muscle relaxers are diazepam, gabapentin, and topiramate.

Local Anesthetics

A person receiving an injection.

Local anesthetics block nerve transmission in the area in which they are applied. Thus, by using local anesthetics in the original area of pain, it will either disappear or diminish.

In addition, these painkillers can also work in structures through which the painful impulse hits the higher nerve centers. This way, the pain won’t be obvious, at least in part. T

Overall, the most popular local anesthetics are lidocaine and pilocarpine.


Finally, these have an effect similar to that of NSAIDs in the sense that they act by inhibiting, or decreasing, inflammation. Then, when inflammation decreases, the pain caused by it also decreases.

A common corticosteroid is prednisone.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.