In a perfect world, the body functions normally and smoothly, however, very often, the body can undergo changes as compared to normal and regular state (homeostasis). During an illness or an environmental change – both internal and external – the body deviates from this homeostasis. As a consequence, various mechanisms are set off which can lead to a myriad of symptoms like fever, fatigue and pain, et cetera. Out of these, the symptom that is most bothersome for patients is pain.

Pain is defined as a highly unpleasant physical sensation caused by illness or injury. Pain can be sharp and horrendous when it is acute in its onset (sudden pain, like in injury), or it can be agonizing when it is chronic (extended over a long period of time).

To relieve pain, there are many pain-killers available in the market but doctors prioritize different pain killers according to the intensity, frequency, cause and character of pain. Where IV pain killers can be used in case of sudden trauma, a different approach is needed in case of chronic pain. Following are some types of painkillers used for chronic pain:

1. Acetaminophen:

Acetaminophen (brand name: Panadol, Tylenol, etc.) is considered as a first line treatment for mild to moderate pain, e.g. trauma, headaches or muscle pain and can help manage osteoarthritis and back pain. It may also be combined with opioids to reduce the amount of opioid needed. Though it is not exactly known how the drug works but scientists think it might inhibit COX-3 (a type of cyclooxygenase enzyme that makes pain-producing prostaglandins).

Acetaminophen is not as effective as NSAIDS (another type of pain killer) but is generally safe for chronic pain management, however, it is contraindicated in alcoholics and in people with renal or hepatic impairment.


“Non-steroidal anti inflammatory drugs” are one of the most common pain killers available in the market. Drugs like Aspirin and Ibuprofen (brand-name: Brufen) are a household name and work by inhibiting both COX-1 and COX-2 inhibitors.

NSAIDS are generally safe for chronic use but they only work up to a certain limit of pain. They may cause nausea, stomach pain, hemorrhages or ulcers as adverse effects. They are also known to cause kidney problems, fluid retention and high blood pressure. The elderly, those with kidney problems, history of stomach ulcers and diabetics, should avoid these drugs.

3. COX-2 inhibitors:

Just like NSAIDS, these also inhibit COX-2 enzymes (but not COX-1). However, these are known to be as effective as NSAIDS, with lesser side-effects like stomach ulcers, hemorrhages, dizziness, nausea, kidney problems, fluid retention and high blood pressure.

Celecoxib (brand name: Celebrex) is used for relieving muscle sprains, strains, back and neck injuries, headaches, menstrual cramps.

4. Antidepressants:

Some antidepressants like amitriptyline, nortriptyline (brand name: Pamelor) and SNRIs like duloxetine, venlafaxine and milnacaprin (Cymbalta, Effexor XR, Savella, respectively) not only treat depression but also help relieve chronic pain, including back pain, fibromyalgia and diabetes-related nerve pain (diabetic neuropathy). Since chronic pain and depression go hand in hand, antidepressants may just hit two birds with one stone. Adverse effects may include nausea, vomiting and dizziness.

5. Antiepileptics

Antiseizure or antiepileptics are used for the treatment of chronic nerve pain, including post herpetic neuralgia and diabetic neuropathy (with stabbing/shooting pain) include gabapentin (Gralise, Neurontin) and pregabalin (brand names: Hilin, Lyrica). Pregabalin is has both anti-inflammatory analgesics and antipyretic properties that fight against joint diseases like osteoarthritis by minimizing friction and roughness between joints and strengthening cartilage.

6. Opioids:

Opioids are a well known class of drugs, the more famous ones being codeine and morphine. Opioids are one of the strongest pain killers available in the market and are notorious for causing dependency with tolerance (deteriorating desired effect), i.e the more drugs taken, the lesser the pain relief.

Opioids work by mimicking endorphins (the body’s natural painkillers) by activating pleasure centers and reducing the pain. This can create an imbalance with the body’s actual levels and there may be changes in breathing, heart rate and alertness. Due to such a wide array of adverse effects, opioids are used as a last-ditch effort, when the former options have not been helpful.

There may be no hard and fast rule as to which drug might be more helpful but the they are tailored according to the patient’s health. They are started off with weaker pain killers to stronger ones if pain has not been managed. It is important to check in regularly with the doctor to report any adverse effect and discuss any concern.