(FDA approved in bold)

• Depression
  
• Migraine prophylaxis
  
• Tension-type headache prophylaxis
  
• Diabetic neuropathy
  
• Post-herpetic neuralgia
  
• Peripheral neuropathy with pain
  
• Back or neck pain
  
• Phantom limb pain
  
• Fibromyalgia
  
• Bulimia nervosa
  
• Insomnia
  
• Anxiety
  
• Nocturnal enuresis
  
• Pseudobulbar affect
  
• Arthritic pain

• Blocks serotonin and norepinephrine reuptake pumps increasing their levels within hours, but antidepressant effect takes weeks. Effect is more likely related to adaptive changes in serotonin and norepinephrine receptor systems over time. It also has antihistamine properties which most likely causes the sedation in treating insomnia

• Migraines – effective in as little as 2 weeks, but can take up to 3 months on a stable dose to see full effect
  
• Neuropathic pain – usually some effect within 4 weeks
  
• Insomnia, anxiety, depression – may be effective immediately, but effects often delayed 2 to 4 weeks

• Migraine – goal is a 50% or greater reduction in migraine frequency or severity. Consider tapering or stopping if headaches remit for more than 6 months or if considering pregnancy
  
• Neuropathic pain – the goal is to reduce pain intensity and symptoms, but usually does not produce remission
  
• Insomnia – continue to use if tolerated and encourage good sleep hygiene

• Increase to highest tolerated dose
  
• Migraine: address other issues, such as medication-overuse, other coexisting medical disorders, such as anxiety, and consider changing to another agent or adding a second agent
  
• Chronic pain: either change to another agent or add a second agent
  
• Insomnia: if no sedation occurs despite adequate dosing, stop and change to another agent

• Migraine: For some patients, low-dose polytherapy with 2 or more drugs may be better tolerated and more effective than high-dose monotherapy. May use in combination with AEDs, antihypertensives, natural products, and non-medication treatments, such as biofeedback, to improve headache control
  
• Chronic pain: AEDs, such as gabapentin, pregabalin, carbamazepine and capsaicin, mexiletine, are agents used for neuropathic pain. Opioids are appropriate for long-term use in some cases but require careful monitoring

• Check ECG for QT corrected (QTc) prolongation at baseline and when increasing dose, especially in those with a personal or family history of QTc prolongation, cardiac arrhythmia, heart failure or recent myocardial infarction. If patient is on diuretics, measure potassium and magnesium at baseline and periodically with treatment