I've taken fluoxetine (Prozac) for several years. But recently, the medication doesn't seem to be having the same effect. Can antidepressants lose effectiveness?

Answer From Daniel K. Hall-Flavin, M.D.

When depression symptoms improve after starting an antidepressant, many people need to continue taking medication long term to prevent symptoms from returning.

However, in some people, a particular antidepressant may simply stop working over time. Doctors don't fully understand what causes the so-called "poop-out" effect or antidepressant tolerance — known as tachyphylaxis — or why it occurs in some people and not in others.

There also can be other reasons an antidepressant is no longer working for you, such as:

  • Worsening depression. It's common for depression symptoms to return or worsen at some point, despite treatment. Called breakthrough depression, symptoms may be triggered by stress or appear with no apparent cause. The current dose of medication you're taking may not be enough to prevent your symptoms when depression gets worse.
  • Another medical condition. Underlying health problems, such as hypothyroidism, can cause or worsen depression.
  • A new medication. Some medications for unrelated conditions can interfere with the way your body breaks down and uses antidepressants, decreasing their effectiveness.
  • Undiagnosed bipolar disorder. Bipolar disorder, formerly called manic-depressive disorder, causes periodic mood swings. While an antidepressant is sometimes used to treat bipolar disorder, a mood-stabilizing or antipsychotic medication is generally needed along with an antidepressant to keep emotional highs and lows in check.
  • Age. In some people, depression gets worse with age. As you get older, you may have changes in your brain and thinking (neurological changes) that affect your mood. In addition, the manner in which your body processes medications may be less efficient. You're also likely to be taking more medications. All of these factors can play a role in depression.

In most cases, depression symptoms get better with adjustments to medication. Your doctor may recommend that you change the dose of your current antidepressant, change to another antidepressant or add another antidepressant or other type of medication to your current treatment. Psychological counseling (psychotherapy) also may help.

Because there are so many reasons depression treatment can stop working, you may need to see a medical doctor who specializes in diagnosing and treating mental illness (psychiatrist) to figure out the best course of action.

Jan. 31, 2018 See more Expert Answers

See also

  1. MIND diet may cut Alzheimer's risk
  2. Addison's disease
  3. Adjustment disorders
  4. Adrenal fatigue: What causes it?
  5. After a flood, are food and medicines safe to use?
  6. Alzheimer's: New treatments
  7. Alzheimer's 101
  8. Caregiver depression
  9. Understanding the difference between dementia types
  10. Alzheimer's: Can a head injury increase my risk?
  11. Mediterranean diet
  12. Alzheimer's disease
  13. Alzheimer's disease: Can exercise prevent memory loss?
  14. Alzheimer's drugs
  15. Alzheimer's genes
  16. Alzheimer's nose spray: New Alzheimer's treatment?
  17. Alzheimer's or depression: Could it be both?
  18. Alzheimer's prevention: Does it exist?
  19. Alzheimer's stages
  20. Alzheimer's test: Detection at the earliest stages
  21. Ambien: Is dependence a concern?
  22. Antidepressant withdrawal: Is there such a thing?
  23. Antidepressants and alcohol: What's the concern?
  24. Antidepressants and weight gain: What causes it?
  25. Antidepressants: Side effects
  26. Antidepressants: Selecting one that's right for you
  27. Antidepressants: Which cause the fewest sexual side effects?
  28. Antiphospholipid syndrome
  29. Antidepressants and pregnancy
  30. Atypical antidepressants
  31. Atypical depression
  32. Axona: Medical food to treat Alzheimer's
  33. Back pain
  34. Bedtime routines: Not just for babies
  35. Benefits of being bilingual
  36. Binge-eating disorder
  37. Blood Basics
  38. Borderline personality disorder
  39. Breast-feeding and medications
  40. Dr. Wallace Video
  41. Parathyroid
  42. Caffeine and depression: Is there a link?
  43. The role of diet and exercise in preventing Alzheimer's disease
  44. Can music help someone with Alzheimer's?
  45. Can't sleep? Try daytime exercise
  46. Hidradenitis suppurativa wound care
  47. Celiac disease
  48. Celiac disease: Can gluten be absorbed through the skin?
  49. Celiac disease diet: How do I get enough grains?
  50. Chase away the winter blues
  51. Child abuse
  52. Chronic traumatic encephalopathy
  53. CJD - Creutzfeldt-Jakob Disease
  54. Clinical depression: What does that mean?
  55. Clinical trials for hidradenitis suppurativa
  56. Coconut oil: Can it cure hypothyroidism?
  57. Coffee after dinner? Make it decaf
  58. Complete blood count (CBC)
  59. Complicated grief
  60. Compulsive sexual behavior
  61. Concussion
  62. Concussion in children
  63. Concussion Recovery
  64. Concussion Telemedicine
  65. Coping with the stress of hidradenitis suppurativa
  66. Coping with the emotional ups and downs of psoriatic arthritis
  67. Creating a hidradenitis suppurativa care team
  68. Creutzfeldt-Jakob disease
  69. Cupping therapy: Can it relieve fibromyalgia pain?
  70. Cushing syndrome
  71. Cyclothymia (cyclothymic disorder)
  72. Delirium
  73. Depression and anxiety: Can I have both?
  74. Depression, anxiety and exercise
  75. Depression: Diagnosis is key
  76. Depression during pregnancy
  77. Depression in women: Understanding the gender gap
  78. Depression (major depressive disorder)
  79. Depression: Provide support, encouragement
  80. Depression: Supporting a family member or friend
  81. Diabetes and depression: Coping with the two conditions
  82. Diagnosing Alzheimer's
  83. Dissociative disorders
  84. Vitamin C and mood
  85. Drug addiction (substance use disorder)
  86. Alzheimer's elder care
  87. Electroconvulsive therapy (ECT)
  88. Empty nest syndrome
  89. Fatigue
  90. Fibromyalgia
  91. Fibromyalgia or not?
  92. Fibromyalgia and acupuncture
  93. Fibromyalgia: Does exercise help or hurt?
  94. Fibromyalgia: Linked to other health problems?
  95. Fibromyalgia pain: Options for coping
  96. Fibromyalgia: Self-care tips
  97. Fibromyalgia and Neurontin
  98. Fish oil and depression
  99. Folic acid supplements: Can they slow cognitive decline?
  100. Foods and sleep
  101. Ginkgo biloba: Can it prevent memory loss?
  102. Global Bridges
  103. HABIT program orientation
  104. Hangover prevention: Do lighter colored drinks help?
  105. Hangovers
  106. Hashimoto's disease
  107. Headache
  108. Hidradenitis suppurativa
  109. Hidradenitis suppurativa and biologics: Get the facts
  110. Hidradenitis suppurativa and diet: What's recommended?
  111. Hidradenitis suppurativa: Tips for weight-loss success
  112. Hidradenitis suppurativa: What is it?
  113. Hidradenitis suppurativa: When does it appear?
  114. How opioid addiction occurs
  115. How to tell if a loved one is abusing opioids
  116. How to use opioids safely
  117. Huperzine A: Can it treat Alzheimer's?
  118. Hyperparathyroidism
  119. Hypoparathyroidism
  120. Hypothyroidism: Can calcium supplements interfere with treatment?
  121. Hypothyroidism diet
  122. Hypothyroidism and joint pain?
  123. Hypothyroidism: Should I take iodine supplements?
  124. Hypothyroidism symptoms: Can hypothyroidism cause eye problems?
  125. Hypothyroidism
  126. Insomnia
  127. Insomnia: How do I stay asleep?
  128. Insomnia treatment: Cognitive behavioral therapy instead of sleeping pills
  129. Intervention: Help a loved one overcome addiction
  130. Is depression a factor in rheumatoid arthritis?
  131. Is fibromyalgia hereditary?
  132. Is the definition of Alzheimer's disease changing?
  133. Depression and diet
  134. Kratom for opioid withdrawal
  135. Lack of sleep: Can it make you sick?
  136. Lexapro side effects: Is breast tenderness common?
  137. Living better with hidradenitis suppurativa
  138. Low blood pressure (hypotension)
  139. Male depression: Understanding the issues
  140. Managing depression in MS
  141. Managing Headaches
  142. Managing hidradenitis suppurativa: Early treatment is crucial
  143. Hidradenitis suppurativa-related health risks
  144. MAOIs and diet: Is it necessary to restrict tyramine?
  145. Marijuana and depression
  146. Mayo Clinic Minute: 3 tips to reduce your risk of Alzheimer's disease
  147. Mayo Clinic Minute: Alzheimer's disease risk and lifestyle
  148. Mayo Clinic Minute New definition of Alzheimer's changes
  149. Mayo Clinic Minute: Prevent migraines with magnetic stimulation
  150. Mayo Clinic Minute Weathering migraines
  151. Mayo Clinic Minute: Women and Alzheimer's Disease
  152. Medication overuse headaches
  153. Meditation
  154. Mediterranean diet recipes
  155. Memory loss: When to seek help
  156. Mental health: Overcoming the stigma of mental illness
  157. Mental health providers: Tips on finding one
  158. Mental health
  159. Mental illness
  160. Migraine
  161. Migraine medications and antidepressants
  162. Migraine treatment: Can antidepressants help?
  163. Infographic: Migraine Treatments: Botox & Nerve Blocking
  164. Migraines and gastrointestinal problems: Is there a link?
  165. Migraines and Vertigo
  166. Migraines: Are they triggered by weather changes?
  167. Alleviating migraine pain
  168. Mild cognitive impairment (MCI)
  169. Mild depression: Are antidepressants effective?
  170. Mindfulness exercises
  171. Monoamine oxidase inhibitors (MAOIs)
  172. Natural remedies for depression: Are they effective?
  173. Nervous breakdown: What does it mean?
  174. New Alzheimers Research
  175. Nicotine dependence
  176. Not tired? Don't go to bed
  177. Occipital nerve stimulation: Effective migraine treatment?
  178. Ocular migraine: When to seek help
  179. Opioids and other drugs: What to watch for
  180. Oppositional defiant disorder (ODD)
  181. Pain and depression: Is there a link?
  182. Pancreatic cancer
  183. Infographic: Pancreatic Cancer: Minimally Invasive Surgery
  184. Pancreatic Cancer Survivor
  185. Pancreatic cancer treatment: Why is it so challenging?
  186. Infographic: Pancreatic Cancers-Whipple
  187. Perimenopause
  188. Perimenopause birth control options
  189. Pet therapy
  190. Phosphatidylserine supplements: Can they improve memory?
  191. Pituitary tumors
  192. Polymyalgia rheumatica
  193. Premenstrual dysphoric disorder
  194. Premenstrual syndrome (PMS)
  195. Prescription drug abuse
  196. Prescription sleeping pills: What's right for you?
  197. Progressive supranuclear palsy
  198. Psychotherapy
  199. Rapidly progressing Alzheimer's: Something else?
  200. Reducing the discomfort of hidradenitis suppurativa: Self-care tips
  201. Salt craving: A symptom of Addison's disease?
  202. Savella may help fatigue
  203. Schizoaffective disorder
  204. Seasonal affective disorder (SAD)
  205. Choosing a light box
  206. Selective serotonin reuptake inhibitors (SSRIs)
  207. Serotonin and norepinephrine reuptake inhibitors (SNRIs)
  208. Skip booze for better sleep
  209. Sleep disorders
  210. Sleep tips
  211. Smoking and rheumatoid arthritis: What's the risk?
  212. Soy: Does it worsen hypothyroidism?
  213. Staying active with hidradenitis suppurativa
  214. Stop your next migraine before it starts
  215. Stress symptoms
  216. Sundowning: Late-day confusion
  217. Support groups
  218. Surgery for hidradenitis suppurativa
  219. Symptom Checker
  220. Tapering off opioids: When and how
  221. Tinnitus and antidepressants
  222. Transcranial magnetic stimulation
  223. Traumatic brain injury
  224. Treating hidradenitis suppurativa: Explore your options
  225. Treating hidradenitis suppurativa with antibiotics and hormones
  226. Treating pain: When is an opioid the right choice?
  227. Treatment-resistant depression
  228. Tricyclic antidepressants and tetracyclic antidepressants
  229. Unexplained weight loss
  230. Vagus nerve stimulation
  231. Valerian: A safe and effective herbal sleep aid?
  232. Vascular dementia
  233. Video: Alzheimer's drug shows early promise
  234. Video: Vagus nerve stimulation
  235. Vitamin B-12 and depression
  236. Vitamin B-12 and Alzheimer's
  237. Vitamin D: Can it prevent Alzheimer's & dementia?
  238. What are opioids and why are they dangerous?
  239. What are the signs and symptoms of hidradenitis suppurativa?
  240. What is reflexology?
  241. Wilson's disease
  242. Wilson's syndrome: An accepted medical diagnosis?
  243. Young-onset Alzheimer's