Antidepressants are used to help treat depression. A number of antidepressants also have pain-relieving properties. These include the older tricyclic antidepressants (TCAs) such as amitriptyline (Elavil), nortriptyline (Aventyl), and desipramine. There are also the newer antidepressants called SNRIs such as duloxetine (Cymbalta) and venlafaxine (Effexor). The SNRIs are less effective than the TCAs but more effective than selective serotonin reuptake inhibitors (SSRIs, described below).
SNRIs, at low doses, have independent pain-relieving properties. At higher doses, they are used for depression. Antidepressants may produce drowsiness, dry mouth, constipation, and weight gain. They may also cause difficulty urinating in older men with an enlarged prostate gland..
Some of the newer antidepressants belong to a family called SSRIs. They increase a chemical called serotonin in the nervous system . The first of these was fluoxetine (Prozac). Now there are a few other drugs including fluvoxamine (Luvox), paroxetine(Paxil), sertraline (Zoloft), citaloprim (Celexa), and escitaloprim (Cipralex). They are not very useful for relieving pain although sometimes patients respond.
Anticonvulsants are used to treat seizures. Some anticonvulsants are useful for pain. Carbamazepine (Tegretol) and oxcarbazepine (Trileptal) are helpful in a type of facial pain called trigeminal neuralgia,.Gabapentin (Neurontin) and pregabalin (Lyrica) can help treat certain chronic pain problems including shingles, diabetic nerve pain, and fibromyalgia. These anticonvulsants have fewer side effects than the tricyclic antidepressants. Side effects of anticonvulsants may include drowsiness, dizziness, weight gain, and swelling of the limbs.
For many years, the only available marijuana-like drugs were marijuana cigarettes or marijuana put into baked goods. These drugs have been used for nausea and pain for years. They were not studied scientifically until more recently. Studies now indicate these drugs can help to treat pain, especially with multiple sclerosis. The more recent marijuana-like drugs include tetrahydrocannabinol (Marinol) and nabilone (Cesamet). There is also the nasal spray tetrahydrocannabinol-cannabidiol (Sativex).
Marijuana-like drugs have many side effects such as drowsiness and changes in mood. Recently, there has been concern about psychosis or psychiatric illness with hallucinations and delusions. These drugs are still in a preliminary state of investigation and use.
A variety of drugs are used for headaches. Acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs) are most common. With headaches, particularly migraines, it is important to take the drugs:
- as early as possible
- in an adequate dose
- in combinations, for example, combining acetaminophen with an over-the-counter NSAID like ibuprofen
- with a drug for nausea such as diphenhydramine (Gravol) or metoclopramide (Maxeran).
There are some drugs that are specific for migraine. These are called the triptans. The oldest is sumatriptan (Imitrex). Other triptans include zolmitriptan (Zomig), naratriptan (Amerge), rizatriptan (Maxalt), and eletriptan (Relpax). Most of these have no major advantage over one other. Drugs like flunarizine (Sibelium), amitriptyline, gabapentin (Neurontin), and topiramate (Topamax) can help prevent migraines.
NOTE: Chronic daily headache can be caused by overuse of common headache drugs. The maximum frequency for taking headache medication is three days a week. Continual use, for example taking one headache pill daily, can result in chronic headache. This is called medication-induced headache. If this happens, ask your health professional about changing your medication or using other strategies.
There are a number of different classes of medications that are referred to as muscle relaxants. They do not actually relax muscles directly, and we do nott know exactly why they help some kinds of pain. They can be extremely sedating, and should not be combined with alcohol or other sedating medications. They are intended to be used for short periods of time only, and there is very little research evidence to show that they are helpful for pain. Some people with chronic pain find them useful for flares (possibly only because they temporarily help you sleep), but they are not a part of everyday treatment. They should not be used by pregnant women or women who could become pregnant.
Local and topical agents
Some pain medicines are used as ointments or creams on the skin. They can also be injected to block nerves to relieve pain. Local anaesthetics may be used in both ways. The injection of local anaesthetics is usually carried out by an anaesthetist. Examples of local anaesthetic drugs include lidocaine (Xylocaine) and EMLA (eutectic mixture of local anaesthetics).
Anaesthetics and creams can be combined with other agents, such as menthol, NSAIDs, and capsaicin. These are available over-the-counter and come in a variety of brand names. Most have not been studied scientifically, but they are widely used. Capsaicin is the active ingredient in red peppers. It reduces pain-producing substances in nerves. Capsaicin commonly causes a burning sensation, making it difficult to use. The lidocaine patch (Lidoderm) is commonly used for shingles pain and other nerve injury pains. However, it is not yet available in Canada. In the United States, it can be easily obtained with a prescription.
Complementary and alternative medications
Complementary and alternative medications include herbal remedies. They may contain active ingredients that have not been adequately tested. These ingredients can be present in varying and often unstated amounts. Complementary and alternative medicines may be hazardous if used with the drugs mentioned above.