SSRIs (Selective Serotonin Reuptake Inhibitors)/SNRIs; Types

Last updated: February 7, 2026Reviewed date: February 7, 2026Reading time: 6 min read
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Selective serotonin reuptake inhibitors (SSRIs) are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder and anxiety disorders. It is an antidepressant that helps to relieve symptoms of depression such as low mood, irritability, feelings of worthlessness, restlessness, anxiety,...

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Article Summary

Selective serotonin reuptake inhibitors (SSRIs) are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder and anxiety disorders. It is an antidepressant that helps to relieve symptoms of depression such as low mood, irritability, feelings of worthlessness, restlessness, anxiety, and difficulty in sleeping. They are one of the most commonly prescribed antidepressants because they are effective at improving mood...

Key Takeaways

  • This article explains Types of Selective serotonin reuptake inhibitors (SSRIs) in simple medical language.
  • This article explains Mechanism of action of Selective serotonin reuptake inhibitors (SSRIs) in simple medical language.
  • This article explains Indications/Uses of Selective serotonin reuptake inhibitors (SSRIs) in simple medical language.
  • This article explains Side Effects of Selective serotonin reuptake inhibitors (SSRIs) in simple medical language.
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Selective serotonin reuptake inhibitors (SSRIs) are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder and anxiety disorders. It is an antidepressant that helps to relieve symptoms of depression such as low mood, irritability, feelings of worthlessness, restlessness, anxiety, and difficulty in sleeping. They are one of the most commonly prescribed antidepressants because they are effective at improving mood with fewer or less severe side effects compared.

Types of Selective serotonin reuptake inhibitors (SSRIs)

Selective serotonin reuptake inhibitors (SSRIs)

  • Citalopram
  • Escitalopram
  • Paroxetine
  • Fluoxetine
  • Fluvoxamine
  • Sertraline

Indalpine and zimelidine were also formerly used as antidepressants but were withdrawn from the market.

Serotonin-norepinephrine reuptake inhibitors (SNRIs)

  • Desvenlafaxine
  • Duloxetine
  • Levomilnacipran
  • Milnacipran
  • Venlafaxine

Serotonin modulators and stimulators (SMS)

  • Vilazodone
  • Vortioxetine

Serotonin antagonists and reuptake inhibitors (SARIs)

  • Nefazodone – withdrawn/discontinued in most countries
  • Trazodone

Etoperidone may also have been formerly used as an antidepressant, but has been discontinued.

Norepinephrine reuptake inhibitors (NRIs)

  • Reboxetine
  • Teniloxazine – also a 5-HT2A receptor antagonist
  • Viloxazine

Although marketed as an antidepressant, a meta-analysis found that reboxetine was ineffective and potentially harmful. Atomoxetine is also sometimes used as an antidepressant but is not specifically approved for this purpose.

Norepinephrine-dopamine reuptake inhibitors (NDRIs)

  • Bupropion – weak NDRI, although its dopaminergic actions are controversial; may act as a norepinephrine-dopamine releasing agent (NDRA) alternatively or additionally; also a non-competitive antagonist of nicotinic acetylcholine receptors

Amineptine and nomifensine were also formerly marketed, but have since been withdrawn due to toxicity. Methylphenidate is also sometimes used as an antidepressant but is not specifically approved for this purpose. Lisdexamfetamine an NDRA was found to be ineffective as an adjunctive antidepressant in phase III clinical trials.

Mechanism of action of Selective serotonin reuptake inhibitors (SSRIs)

In the brain, messages are passed from a nerve cell to another via a chemical synapse, a small gap between the cells. The presynaptic cell that sends the information releases neurotransmitters including serotonin into that gap. The neurotransmitters are then recognized by receptors on the surface of the recipient postsynaptic cell, which upon this stimulation, in turn, relays the signal. About 10% of the neurotransmitters are lost in this process; the other 90% are released from the receptors and taken up again by monoamine transporters into the sending presynaptic cell, a process called reuptake.SSRIs inhibit the reuptake of serotonin. As a result, the serotonin stays in the synaptic gap longer than it normally would, and may repeatedly stimulate the receptors of the recipient cell. In the short run, this leads to an increase in signaling across synapses in which serotonin serves as the primary neurotransmitter. On chronic dosing, the increased occupancy of post-synaptic serotonin receptors signals the pre-synaptic neuron to synthesize and release less serotonin. Serotonin levels within the synapse drop, then rise again, ultimately leading to downregulation of post-synaptic serotonin receptors. Other, indirect effects may include increased norepinephrine output, increased neuronal cyclic AMP levels, and increased levels of regulatory factors such as BDNF and CREB. Owing to the lack of a widely accepted comprehensive theory of the biology of mood disorders, there is no widely accepted theory of how these changes lead to the mood-elevating and anti-anxiety effects of SSRIs.

Indications/Uses of Selective serotonin reuptake inhibitors (SSRIs)

SSRIs or SNRIs are used primarily in the clinical treatment of mood disorders such as

Contra-Indications

  • Syndrome of inappropriate antidiuretic hormone secretion
  • Low amount of magnesium in the blood
  • Low amount of sodium in the blood
  • Low amount of potassium in the blood
  • Increased risk of bleeding
  • Behaving with excessive cheerfulness and activity
  • A mild degree of mania
  • Manic-depression
  • Having thoughts of suicide
  • Neuroleptic malignant syndrome
  • Serotonin syndrome – adverse drug interaction
  • Closed-angle glaucoma
  • Heart attack within the last 30 days
  • Very Rapid Heartbeat – Torsades de Pointes
  • Prolonged QT interval on EKG
  • Heart Disease
  • Abnormal EKG with QT changes from Birth
  • Liver problems
  • Bleeding from Stomach
  • Esophagus or Duodenum
  • Severe renal impairment
  • Seizures
  • Risk of angle-closure glaucoma due to narrow-angle of the anterior chamber of the eye

Side Effects of Selective serotonin reuptake inhibitors (SSRIs)

The most common

More common

Less common

  • Abnormal dreams
  • change in sense of taste
  • congestion
  • discouragement, feeling sad, or empty
  • Suicide attempts
  • Acting on dangerous impulses
  • Aggressive or violent behavior
  • Thoughts about suicide or dying
  • New or worse depression
  • New or worse anxiety or panic attacks
  • Agitation, restlessness, anger, or irritability
  • Trouble sleeping
  • An increase in activity or talking more than normal

Drug Interactions

SSRIs & SNRIs  may interact with the following drugs, supplements & may decrease the efficacy of the drug

  • antihistamines (e.g, cetirizine, doxylamine, diphenhydramine, hydroxyzine, loratadine)
  • antipsychotic medications (e.g., chlorpromazine, haloperidol, olanzapine, quetiapine, risperidone)
  • barbiturates (e.g., butalbital, pentobarbital, phenobarbital)
  • benzodiazepines (e.g., alprazolam, diazepam, lorazepam)
  • beta-blockers (e.g., carvedilol, metoprolol, propranolol)
  • bupropion
  • captopril
  • carvedilol
  • celecoxib
  • chloral hydrate
  • chloroquine
  • cilostazol
  • celecoxib
  • clopidogrel
  • dasatinib
  • insulin is low or not working well. সহজ বাংলা: রক্তে চিনি বেশি থাকার রোগ।" data-rx-term="diabetes" data-rx-definition="Diabetes is a condition where blood sugar stays too high because insulin is low or not working well. সহজ বাংলা: রক্তে চিনি বেশি থাকার রোগ।">diabetes medications (e.g., chlorpropamide, glipizide, glyburide, insulin, metformin, nateglinide, rosiglitazone)
  • domperidone
  • glucosamine
  • heparin
  • herbal products that affect blood clotting (e.g., cat’s claw, chamomile, fenugreek, evening primrose, feverfew, garlic, ginger, ginseng, turmeric)
  • ketoconazole
  • losartan
  • low molecular weight heparins (e.g., dalteparin, enoxaparin, tinzaparin)
  • macrolide antibiotics (e.g., clarithromycin, erythromycin)
  • MAO inhibitors (e.g., linezolid, moclobemide, phenelzine, selegiline, tranylcypromine)
  • mirabegron
  • multivitamins/minerals
  • muscle relaxants (e.g., baclofen, cyclobenzaprine, methocarbamol, orphenadrine, tizanidine)
  • methamphetamine
  • metoclopramide
  • metoprolol
  • narcotic pain relievers (e.g., codeine, fentanyl, methadone, morphine, oxycodone)
  • nonsteroidal  infection, or irritation, often causing pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।" data-rx-term="inflammation" data-rx-definition="Inflammation is the body’s response to injury, infection, or irritation, often causing pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।">inflammation, pain, or swelling. সহজ বাংলা: প্রদাহ/ফোলা/ব্যথা কমায়।" data-rx-term="anti-inflammatory" data-rx-definition="Anti-inflammatory means reducing inflammation, pain, or swelling. সহজ বাংলা: প্রদাহ/ফোলা/ব্যথা কমায়।">anti-inflammatory medications (NSAIDs; diclofenac, ibuprofen, naproxen)
  • omega-3 fatty acids
  • pentoxifylline
  • quinolone antibiotics (e.g., levofloxacin, moxifloxacin)
  • seizure medications (e.g., carbamazepine, clobazam,  felbamate, levetiracetam, phenobarbital, phenytoin, primidone, topiramate, valproic acid, zonisamide)
  • serotonin/norepinephrine reuptake inhibitors (SNRIs e.g., desvenlafaxine, duloxetine, venlafaxine)
  • other selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, )
  • 5-HT3 antagonists (e.g., granisetron, ondansetron)
  • tamsulosin
  • tapentadol
  • thiazide diuretics (e.g., hydrochlorothiazide, indapamide)
  • tramadol
  • tricyclic antidepressants (e.g., nortriptyline, amitriptyline, imipramine, desipramine)
  • tyrosine kinase inhibitor (e.g., imatinib, lapatinib, pazopanib, sunitinib)
  • vitamin E
  • warfarin

References

SSRIs (Selective Serotonin Reuptake Inhibitors)/SNRIs; Types

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Safety note: This is not a prescription or diagnosis. For severe symptoms, pregnancy danger signs, children with serious illness, chest pain, breathing difficulty, stroke-like weakness, or major injury, seek urgent care.

Which doctor may help?

Start with a registered doctor or the nearest qualified health center.

What to tell the doctor

  • Write when the problem started and how it changed.
  • Bring old prescriptions, investigation reports, and current medicines.
  • Write allergies, pregnancy status, diabetes, kidney/liver disease, and major past illnesses.
  • Bring one family member if the patient is weak, elderly, confused, or a child.

Questions to ask

  • What is the most likely cause of my symptoms?
  • Which danger signs mean I should go to hospital quickly?
  • Which tests are necessary now, and which can wait?
  • How should I take medicines safely and what side effects should I watch for?
  • When should I come for follow-up?

Tests to discuss

  • Vital signs: temperature, pulse, blood pressure, oxygen saturation
  • Basic physical examination by a clinician
  • CBC, urine test, blood sugar, or imaging only when clinically needed

Avoid these mistakes

  • Do not use antibiotics, steroid tablets/injections, or strong painkillers without proper medical advice.
  • Do not hide pregnancy, kidney disease, ulcer, allergy, or blood thinner use.
  • Do not delay emergency care when danger signs are present.

Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

  • Avoid heavy lifting, sudden bending, and prolonged bed rest.
  • Use comfortable posture and gentle movement as tolerated.
  • Discuss physiotherapy, X-ray, or MRI only when clinically needed.

OTC medicine safety

  • For mild back pain, pain-relief medicine may be discussed with a doctor or pharmacist.
  • Avoid repeated painkiller use if you have kidney disease, stomach ulcer, uncontrolled blood pressure, or are taking blood thinners.

Avoid these mistakes

  • Do not start antibiotics without a proper medical decision.
  • Do not use steroid tablets or injections casually for quick relief.
  • Do not delay emergency care because of home remedies.

Get urgent help if

  • Back pain with leg weakness, numbness around private area, loss of urine/stool control, fever, cancer history, or major injury needs urgent care.
Medicine names, dose, and timing must be decided by a qualified clinician or pharmacist after checking age, pregnancy, allergy, other diseases, and current medicines.

For rural patients and family caregivers

Patient health record and symptom diary

Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Orthopedic / spine specialist, physical medicine doctor, or qualified clinician
Tests to discuss with doctor
  • Neurological examination for leg power, sensation, reflexes, and straight leg raise
  • X-ray only if injury, deformity, long-lasting pain, or doctor suspects bone problem
  • MRI discussion if severe nerve symptoms, weakness, bladder/bowel problem, or persistent symptoms
Questions to ask
  • What is the most likely cause of my symptoms?
  • Which warning signs mean I should go to emergency care?
  • Which tests are really needed now?
  • Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?
  • Is physiotherapy, posture correction, or activity modification needed?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Safe pathway to proper treatment

Care roadmap for: SSRIs (Selective Serotonin Reuptake Inhibitors)/SNRIs; Types

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

RX Patient Help

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Write your symptom story. A health professional or site editor can review it before any answer is prepared. This box is not for emergency care.

Emergency first: Severe chest pain, breathing trouble, unconsciousness, stroke signs, severe injury, heavy bleeding, or rapidly worsening symptoms need urgent local medical care now.

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

Add references, clinical guidelines, textbooks, journal articles, or trusted medical sources here. You can edit this area from the RX Article Professional Blocks panel.

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