Pain killers

Analgesic is a general name for types of painkillers that do not cause unconsciousness. A large variety of analgesics are used in ME/CFS to help relieve both chronic and acute pain. They are also used to treat pain associated with comorbid illnesses such as IBS or endometriosis.

Analgesics act in a variety of ways on the peripheral and central nervous systems and can be taken in combination or alone.

Determining which analgesic is appropriate involves considering both the severity and type of pain presented. The patient's response to previous analgesics may also be considered.

Acetaminophen
Acetaminophen, also known as paracetamol or Tylenol, is used to treat mild to moderate pain and fever. It is classed as a mild analgesic and does not reduce inflammation. Acetaminophen can be taken by mouth (tablets or liquid), rectally (as suppositories), or intravenously, and is typically taken every four and six hours as needed. Extended release acetaminophen can be taken every 8 hours. Typical uses include headaches, muscle aches, colds and sore throats, back pain, toothaches), and to reduce fever. It is usually available over the counter without a prescription. Taking too much acetaminophen, or taking more than one product containing it can cause severe liver damage or death.

Some pain medications combine acetaminophen with other drugs, for instance with NSAIDs (Anacin, Excedrin), or opioids (Hycet, Percocet, co-codamol), for stronger pain relief.

Acetaminophen for pain caused by M.E.
Acetaminophen can be used as a baseline drug for pain; it has a weak effect but few side effects.

NSAIDs
Nonsteroidal anti-imflammatory drugs are a class of drugs which provide both analgesic (pain-killing) and antipyretic (fever-reducing) effects, and anti-inflammatory effects in higher doses. They range from mild to strong pain relief. 

Commonly used NSAIDs include aspirin, ibuprofen, naproxen, diclofenac, celecoxib, meloxicam, mefenamic acid, and nabumetone.

Suggested NSAIDs for pain caused by M.E.
ibuprofen, naproxen, and celecoxib, a COX-2 inhibitor. Ketorolac is a NSAID which can be used for up to 5 days, for example after surgery, and is available as tablets, by intramuscular injection or IV.

COX-2 inhibitors
COX-2 inhibitors are NSAIDs that directly target cyclooxygenase-2 (COX-2), an enzyme responsible for inflammation and pain. Some COX-2 inhibitors used in ME/CFS include celecoxib and meloxicam.

Opioids
Opioids are drugs that bind to opioid receptors to produce morphine-like effects. They provide moderate to very strong pain relief. Some of these are codeine, tramadol, oxycodone, vicodin, hydrocodone, fentanyl and morphine. A large number of opiods may be used in M.E./CFS.

Tricyclic Antidepressants
Tricyclic antidepressants (TCAs) are a group of medications which are licensed for many different conditions besides depression, including Chronic Myofascial Pain, Dysautonomia (amitriptyline, nortriptyline, desipramine), long-term pain (amitriptyline, nortriptyline, imipramine), Fibromyalgia (amitriptyline), Irritable Bowel Syndrome (amitriptyline, nortriptyline, doxepin, and others), Migraine prevention (amitriptyline, nortriptyline), Neuralgia (nerve pain), and sleep paralysis. TCAs include amitriptyline, nortriptyline or clomipramine are commonly used in ME/CFS to treat chronic pain and to aid regular sleep.

TCAs suggested for pain in M.E.
Most patients with M.E. are extremely sensitive to medication; the International Consensus Primer for Medical Practitioners recommends starting with a lower initial dose of TCAs, and that they should be used short term only. There is evidence that Amitriptyline, Nortriptyline and Doxepin are effective for pain caused by M.E.; like all TCAs benefits may not take effect for 2-4 weeks The sedating effects of Doxepin and Amitriptyline may help patients with sleep problems remain asleep. Side effects may be severe, and include morning or daytime sleepiness, dry mouth, weight gain, and increase dizziness and orthostatic intolerance. Amitriptyline may also cause cognitive dysfunction, e.g. brain fog. Nortriptyline causes the least side effects, and Amitriptyline is particularly effective for people with Fibromyalgia. Some guidance states these drugs should be avoided in overweight patients with M.E.

Anticonvulsants
Anticonvulsants are a group of medications that were originally used in the treatment of epileptic seizures, but are increasingly used for other purposes, including the treatment of neuropathic pain. Anticonvulsants commonly used for pain in ME/CFS include GABA analogs such as gabapentin (Neurontin) and pregabalin (Lyrica), and fatty acids such as tiagabine (Gabitril).

Medical marijuana
Medical marijuana in various forms is increasingly used to treat chronic pain, including neuropathic pain. CBD oil, made from marijuana or hemp, is also gaining popularity as an analgesic.

Others
Other analgesic treatments for chronic pain include lidocaine infusions, ketamine infusions, steroid injections such as cortisone, and benzodiazepines such as diazepam. Low dose naltrexone has also been reported to reduce chronic pain in ME/CFS and fibromyalgia. A variety of supplements and herbs are also used to reduce pain.

For non-pharmacological pain relief such as TENS or massage therapy, see pain management.

Learn More
Over-the-counter pain relievers: MedlinePlus

Myalgic Encephalomyelitis - Adult & Paediatric International Consensus Primer for Medical Practitioners, p13, p17