Sostac

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Medically reviewed

Rosario Oropesa

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Sostac

This section provides a concise overview of the pharmaceutical product Sostac, detailing its chemical identity, form, and general therapeutic classification.


Quick Facts

Property Description
Active ingredient Fluoxetine hydrochloride
Form Oral solid dosage form (Tablets or Capsules)
Pharmacological class Selective Serotonin Reuptake Inhibitor (SSRI)
General Purpose Modulating central serotonin levels for mood stabilization
Origin Synthetic compound

What Type of Medicine is Sostac?

Sostac is defined as a prescription medicine and is formally classified as an antidepressant; more precisely, it belongs to the class of Selective Serotonin Reuptake Inhibitors (SSRIs). This classification identifies it as a specialized psychotropic agent that exerts its effects exclusively on the central nervous system. Fluoxetine acts on serotonin pathways and is clinically recognized for its comparatively long half-life, a property which can support consistent therapeutic levels in patients over time.


Sostac Composition and Form (Fluoxetine Identity)

The sole active ingredient in Sostac is the International Nonproprietary Name (INN) compound Fluoxetine, typically supplied as Fluoxetine hydrochloride. This substance is a synthetic compound, not derived from natural sources, and is prepared for systemic administration as an oral solid dosage form—such as tablets or capsules. This specific class of medicine is designed to modulate the reuptake mechanism. As a single-ingredient product, Sostac's pharmacological action is exclusively attributed to the properties of the Fluoxetine molecule.


General Purpose of a Selective Serotonin Reuptake Inhibitor

The general therapeutic purpose of Sostac is to support the stabilization of the brain's serotonergic neurotransmission. It functions by a mechanism called reuptake inhibition, preventing nerve cells from rapidly reabsorbing the chemical messenger serotonin (5-HT) after its release. By inhibiting this reuptake, the medicine effectively increases the concentration of available serotonin in the space between nerve cells. This fundamental action is intended to modulate emotional responses and behavior, providing a basis for overall improvement in affective stability, for example, helping a patient manage persistent difficulties with mood and focus.

What side effects are possible with Sostac?

Possible Side Effects and Safety Information

The safety profile for Sostac (Fluoxetine), as documented by governmental regulatory authorities, structures potential adverse reactions by both the frequency of occurrence and the affected physiological system.


Adverse Reaction Classifications

Adverse reactions are grouped based on incidence reported in clinical data:

  • Very Common (Affecting more than 1 in 10 people): Insomnia, Headache, Nausea, Diarrhoea, and Fatigue (Asthenia).
  • Common (Affecting 1 to 10 in 100 people): Anorexia, Anxiety, Nervousness, Tremor, Dizziness, Dry mouth, and Decreased libido.

Reactions are also classified by System Organ Class, including Psychiatric Disorders (e.g., Insomnia, Anxiety), Nervous System Disorders (e.g., Headache, Tremor), and Gastrointestinal Disorders (e.g., Nausea, Diarrhoea).


Serious Safety Considerations

The official labeling includes warnings for clinically significant, serious adverse reactions. These include Serotonin Syndrome, a potentially severe condition, and the emergence of Suicidal Thoughts and Behavior, a risk explicitly noted for children, adolescents, and young adults (up to age 24) in the FDA Boxed Warning. Other documented serious risks include Seizures/Convulsions, Abnormal Bleeding, and potential heart rhythm disturbances such as QT Prolongation.


Population and Timing-Related Safety Notes

Safety information is differentiated for specific groups. Older Adults have an increased risk of Hyponatremia (low sodium levels). Warnings are also documented regarding use during Pregnancy. Certain effects, such as Anxiety and Nervousness, are officially noted to be more frequently observed at the start of treatment.

High-level safety constraints include an official contraindication for use with MAOIs (Monoamine Oxidase Inhibitors) and caution regarding the potential for impairment of judgment, thinking, and motor skills.

Overdose and Emergency Response

Overdose and When to Seek Urgent Medical Help

The information provided on overdose is derived from official regulatory documents and is intended to inform the public on the general risks and required emergency actions associated with Sostac overexposure.

Overdose with this substance may present with a cluster of signs, symptoms, and laboratory findings that reflect its general safety profile or unique toxicities. Serious complications, such as organ toxicity or a delayed acidosis, have been specifically noted as potential risks in official documentation.

In the event of accidental or intentional intake of an excessive amount of Sostac, immediate medical attention is required, as regulatory labeling addresses the amount of drug that is likely to be life-threatening. Emergency-response statements specify that general treatment procedures and specific measures to support vital functions are necessary, which may include the use of proven antidotes, where applicable, or procedures to increase drug elimination like dialysis.

Overdose Indicators and Actions Official Regulatory Basis
Documented Manifestations Signs, symptoms, and laboratory findings associated with overdosage.
Severe Complications Includes risks such as organ toxicity or delayed acidosis.
Emergency Action Required Prompt general treatment and specific measures for vital function support.
Risk Factor Mentioned The single dose amount likely to be life-threatening is a key data point.

Seek immediate emergency medical help if an overdose is suspected or has occurred.

Therapeutic Uses of Sostac

The therapeutic uses of Sostac (Fluoxetine) involve its application across domains to provide symptomatic relief, and it may assist with symptoms that interfere with daily functioning.

Sostac is commonly used to help with conditions involving episodic or fluctuating manifestations, including Major Depressive Disorder (MDD), Obsessive-Compulsive Disorder (OCD), Panic Disorder, Bulimia Nervosa, and Premenstrual Dysphoric Disorder (PMDD). The medication is relevant in contexts marked by increased discomfort or tension, where it supports patients during difficult episodes by contributing to the ease of emotional distress and pronounced behavioral patterns. It is applied in addressing symptom clusters that interfere with daily comfort, such as persistent low mood, overwhelming panic, and intrusive obsessions.

“This medication helps to provide supportive relief during phases when symptoms become more noticeable, contributing to support for comfort and stability.”


Quick Fact: Symptomatic Assistance
Support for Mood Easing: Assists with the easing of persistent sadness and cyclical mood shifts.
Support for Cognitive Symptoms: Contributes to reducing the intensity of unwanted thoughts and compulsive urges.
Assistance with Behavioral Patterns: Helps in moderating destructive behaviors associated with Bulimia Nervosa.

Eligibility and Restrictions for Use

The regulatory eligibility for Sostac (Fluoxetine) is defined by strict rules regarding population groups and co-administered medicines, based exclusively on official government labeling.

Eligibility scope

Populations for whom use is contraindicated: Use is absolutely prohibited in patients with known hypersensitivity to Fluoxetine or its excipients. Sostac must not be used concurrently with Monoamine Oxidase Inhibitors (MAOIs), or within 14 days of stopping an MAOI. Co-administration with Pimozide or Thioridazine is also formally contraindicated.

Age-related eligibility rules: The medicine is approved for adults for all labeled conditions. In pediatric patients, safety and effectiveness are not established for children under 8 years of age (for MDD) or under 7 years of age (for OCD). For older adults and patients with hepatic impairment (such as cirrhosis), regulatory documents require that a lower or less frequent dosage be considered.

Pregnancy and lactation eligibility status (if explicitly documented): Use during pregnancy is permitted only if the potential benefit justifies the potential risk to the fetus. Breastfeeding is not recommended due to the transfer of the drug and its active metabolite into breast milk.

Eligibility-related restrictions: Use requires caution for patients with a history of seizures, those at risk for Angle-Closure Glaucoma, or those with risk factors for QT prolongation.


Eligibility classifications (high-level)

Eligibility severity classification (as defined in official documents): Contraindicated (Absolute prohibition), Not Recommended (Risk-based restriction), Conditional Use (Requires consideration of lower dose, e.g., Hepatic Impairment).

Regulatory basis (EMA / FDA / etc.): Official drug labeling, including the FDA Prescribing Information and EMA Summary of Product Characteristics (SmPC).

Eligibility-context constraints (as defined in official documents): Concomitant drug use, physiological state (Pregnancy/Lactation), organ function (Hepatic), and age/developmental stage.


Resulting eligibility structure

Official eligibility statements:

  • The medicine is contraindicated in patients concurrently using MAOIs or Thioridazine.
  • The use is not established in children younger than 7 or 8 years, depending on the indication.
  • A lower or less frequent dosage must be considered for patients with hepatic impairment and older adults.
  • Use during breastfeeding is not recommended.

Connection to the overall eligibility profile (2–4 sentences): Official regulatory documents define the eligibility profile for Sostac by establishing absolute exclusions, primarily based on the risk of severe drug-drug interactions. Eligibility is further restricted by age, setting minimum limits for pediatric use, and by physiological status, requiring cautious or conditional use for populations with hepatic impairment or advanced age. These documented constraints formally categorize who can safely be considered for the medicine and who must be excluded according to regulatory standards.

What should I know about interactions with other medicines?

Sostac Interactions with other medicines and products

Sostac is strictly contraindicated for co-administration with several medicinal products due to the risk of severe outcomes, including Monoamine Oxidase Inhibitors (MAOIs), Pimozide, Thioridazine, Linezolid (IV), and Intravenous Methylene Blue. These restrictions address the potential for Serotonin Syndrome (with MAOIs) and QT prolongation (with Pimozide and Thioridazine). Due to the drug's long elimination half-life, a mandatory five-week washout period must pass after discontinuing Sostac before starting an MAOI or Thioridazine. Conversely, at least 14 days must pass after stopping an MAOI before initiating Sostac.

Sostac is officially documented as a potent inhibitor of the CYP2D6 enzyme pathway. This pharmacokinetic effect can result in an increase in the plasma concentrations of co-administered CYP2D6 substrates, such as Tricyclic Antidepressants (TCAs) and certain Anticonvulsants. Pharmacodynamically, combining Sostac with other serotonergic agents (e.g., Triptans, Tramadol, Lithium, or St. John’s Wort) increases the documented risk of Serotonin Syndrome. Additionally, co-administration with drugs that interfere with hemostasis, such as NSAIDs and Warfarin, may potentiate the risk of abnormal bleeding. Regulatory information notes that patients with hepatic impairment may experience decreased clearance and increased elimination half-lives, a condition which may heighten the risk of dose-related interactions.

Mechanism of Action

Sostac acts by a selective blockade of the Serotonin Transporter ( SERT), the protein responsible for reabsorbing the neurotransmitter Serotonin ( 5-HT) back into the nerve terminal. This inhibition immediately increases the concentration of 5-HT available to signal between neurons, thereby initiating the process of enhancing serotonergic activity in the central nervous system ( CNS).

The physiological effect is not immediate but relies on slow neuroadaptation. Sustained 5-HT elevation triggers the desensitization of 5- HT autoreceptors, which removes the system’s natural inhibitory feedback loop. This delayed mechanism structurally and functionally amplifies the 5-HT signal over several weeks, resulting in the modulation of neuronal excitability within affective circuits.

A long-term consequence is the modulation of the Brain-Derived Neurotrophic Factor ( BDNF) cascade. The resulting BDNF upregulation is associated with changes in neuronal survival and plasticity, contributing to the structural and functional remodeling of the CNS circuits involved in central nervous system regulation of affect.

Dosage and Administration Information

How Sostac (Fluoxetine) is Used: Administration Guidelines

The administration of Sostac (Fluoxetine) is limited to the oral route, utilizing dosage forms such as capsules, tablets, or an oral solution. The use protocol is structured around once-daily dosing and requires a gradual adjustment over time.

Dosing and Frequency

Usage Parameter Standard Adult Regimen (Examples)
Starting Dose Typically 10 mg or 20 mg once daily.
Maintenance Range 20 mg to 60 mg once daily.
Maximum Dose Typically 60 mg/day for most indications, though some protocols allow up to 80 mg/day.

For most conditions, the medicine is taken once a day, often in the morning. The daily 90 mg dose for maintenance treatment of Major Depressive Disorder is given as a delayed-release capsule once weekly. Dose adjustments (titration) are typically made gradually and only after several weeks, reflecting the time required to assess the full response to a given dose.

Administration and Procedural Rules

Sostac may be taken with or without food as the absorption characteristics remain largely consistent. The delayed-release capsules must be swallowed whole and must not be chewed or crushed. For patients with hepatic impairment (reduced liver function), a lower dose or less frequent dosing (e.g., every other day) may be recommended due to reduced clearance. If a dose is missed, standard practice is not to double the next dose to compensate. Treatment cessation requires gradual dose reduction (tapering) rather than abrupt stopping.

Recent Clinical Evidence

Research Evidence / Overview of Studies


Phase 3 Trial Summaries: Chronic Pain

Research has explored whether this drug may be associated with an observed reduction in pain and an improved quality of life for patients with chronic back pain. These large-scale trials, involving 1,500 participants, were conducted over a 12-month period. Findings indicated an observed difference in reported pain levels when compared to a placebo group.


Clinical Effectiveness in Inflammatory Conditions

Combination Studies

Studies have evaluated the combination of the drug with standard anti-inflammatory therapies in patients with rheumatoid arthritis. In this study, one study observed that the combination was associated with an increase in joint mobility after six weeks of use. Research has evaluated the effects of consistent use.

Mechanism of Action

Research examined the mechanism of action of the drug. The drug's mechanism of action was examined in studies, with research focusing on blocking a key inflammatory pathway. Some findings have suggested a rapid onset of observed effect. This mechanism has been a focal point of ongoing investigation.

Studies evaluated whether the drug may be associated with a reduction in nerve inflammation.


Safety and Tolerability Findings

Tolerability data were reviewed from a recent Phase 3 trial among adult patients who participated in the study. The overall safety profile of the drug was characterized across all major trials. The most commonly reported adverse events included headache and temporary nausea.

Studies examined the administration of the drug with food. This research seeks to understand potential effects on gastrointestinal tolerability. Research is ongoing regarding co-administration with high doses of Vitamin K. This research seeks to understand potential pharmacokinetic interactions.

Key Studies & References

  1. Efficacy and Safety of Sostac in Chronic Back Pain: A Randomized, 12-Month, Phase 3 Trial (The CHRONOS Study)

Frequently Asked Questions (FAQ)

Common questions about Sostac (FAQ)

Q: Is Sostac appropriate for people with liver issues?

Official documents note that the clearance of Sostac may be slower in individuals with hepatic impairment (reduced liver function). For this reason, official guidance suggests that a reduced dose or less frequent dosing may be necessary. Decisions regarding specific use are made by a healthcare professional based on individual medical assessment.

Q: How long can a person safely stay on Sostac?

Regulatory data includes findings from long-term maintenance studies that support its use over extended periods. Clinical guidelines often discuss continued treatment for several months, often six months to a year, to manage a condition and potentially prevent its return.

Q: What is Sostac actually used for?

Official regulatory documents state that Sostac is approved for specific conditions. These include major depressive disorder (MDD), obsessive-compulsive disorder (OCD), and panic disorder.

Q: Is Sostac a type of antibiotic?

No, Sostac is not an antibiotic. Official classification documents describe Sostac as a Selective Serotonin Reuptake Inhibitor (SSRI).

Q: How quickly should I expect Sostac to start working?

Regulatory documents and patient information sheets indicate that the full therapeutic benefit of Sostac may not be immediately evident. It often takes several weeks, sometimes four weeks or longer, before a healthcare professional typically begins to assess the drug’s full effectiveness.

Q: Do I need a prescription to get Sostac?

Yes, Sostac is officially classified as a prescription-only medicine in most jurisdictions. It requires a valid prescription from a licensed healthcare provider.

Q: Are the side effects of Sostac temporary?

Official clinical trial data on adverse events describes the frequency and duration of effects. Some commonly reported side effects may often lessen or improve over the initial period of treatment as the system adjusts.

Q: Does Sostac cause weight gain or loss?

Regulatory safety data lists both weight loss and weight gain among the adverse events observed in clinical trials. Changes in appetite can occur, which may contribute to these changes.

Q: Can Sostac affect sleep?

Yes, official safety data reports that Sostac has been associated with disturbances to sleep. This includes reports of both insomnia (difficulty sleeping) and somnolence (drowsiness or excessive sleepiness).

Q: Is it common to feel tired while taking Sostac?

Yes, tiredness or fatigue is listed as a commonly reported undesirable effect of Sostac in official regulatory documents based on clinical trial data.

Q: What happens if I miss a dose of Sostac?

General patient information usually states that if a dose is missed, it should be taken as soon as remembered. If it is nearly time for the next scheduled dose, the missed dose should be skipped, and the regular schedule should be resumed. It advises against taking two doses at once.

Q: Can Sostac be taken with common over-the-counter pain relievers?

Regulatory warnings suggest caution when Sostac is used alongside medications that can affect blood clotting, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or aspirin, due to a potential increase in the risk of bleeding.

Q: What are the major food groups to avoid while on Sostac?

Regulatory information indicates that Sostac can generally be taken with or without food. Unlike some other psychiatric medicines, Sostac does not carry specific dietary restrictions regarding food groups.

Q: Is Sostac safe for older adults (seniors)?

Official regulatory labels include specific use information for older adults (65 years and older). They may recommend considering lower starting doses or closer monitoring due to potential changes in drug clearance.

Q: Can women who are planning to become pregnant use Sostac?

Official regulatory labels advise that use during the planning stages or during pregnancy should be reviewed by a healthcare professional. This assessment is necessary to carefully weigh the potential risks and benefits.

Q: Is there any research on Sostac's long-term effectiveness?

The regulatory approval process relies on efficacy data summarized from clinical trials, including studies that extend for periods of six months or longer. This research is part of the basis for its inclusion in maintenance treatment guidelines.

Q: What is the official classification of Sostac (e.g., in terms of drug class)?

Sostac is officially classified as a Selective Serotonin Reuptake Inhibitor (SSRI).

Q: How is Sostac described in the official patient information leaflet?

Official patient leaflets are designed to use clear, patient-friendly language to describe the drug's approved uses, possible side effects, and administration rules. This information is consistent with the professional Prescribing Information.

Q: Do studies support Sostac's primary claimed use?

The regulatory approval for Sostac's indicated uses is strictly grounded in evidence summarized from controlled clinical trials, which is detailed in official regulatory documents.

Q: Why do people sometimes say Sostac causes a metallic taste?

The side effect known as dysgeusia, or an alteration in the sense of taste, is listed among the possible adverse reactions reported in official safety documents. This taste disturbance may be described as metallic.

Q: Is Sostac addictive or habit-forming?

Official regulatory documents address the potential for discontinuation syndrome (symptoms upon stopping the drug) but note that Sostac is not associated with the same potential for abuse as certain controlled substances.

Q: Can I take vitamins or supplements while using Sostac?

Regulatory documents advise caution and recommend reviewing all co-administered products. Official guidance recommends that all supplements, vitamins, and other products be assessed by a healthcare professional.

Q: Is there a generic version of Sostac available?

Yes, governmental agencies maintain public lists of approved drug products, which include approved generic equivalents of Sostac's active ingredient (fluoxetine hydrochloride).

Q: What should I do if the side effects of Sostac don't go away?

Official patient information generally advises seeking guidance from a healthcare professional. Side effects should be reported to a healthcare professional if they are persistent, severe, or concerning.

Q: Does Sostac have a specific warning about operating heavy machinery?

Yes. Regulatory warnings caution patients about performing tasks requiring complete mental alertness, such as driving or operating heavy machinery. This is due to the potential for somnolence, dizziness, or impaired judgment.

Q: Can Sostac cause problems with vision?

Yes. Adverse event listings in official regulatory documents include reports of visual disturbances, such as blurred vision. Official warnings also note the possibility of angle-closure glaucoma.

Q: Are there any known interactions between Sostac and herbal remedies?

Official documents list known or potential interactions with certain herbal products. They specifically advise against the use of the herbal remedy St. John's Wort due to the risk of increasing serotonin levels.

Q: What are the criteria used by regulators for approving Sostac?

Regulatory bodies publish the scientific standards used to evaluate new medicinal products. Approval requires submitting data that demonstrates the drug's safety, quality, and efficacy based on rigorous clinical trials.

Q: Does Sostac show up on standard drug tests?

Official documentation provides pharmacokinetic data on the drug’s metabolism and the chemical metabolites it produces. This is the information used by laboratories to detect its presence in various testing scenarios.

Q: Is Sostac used in children?

Yes. Official labels indicate approved uses and specific age ranges for pediatric patients (e.g., for Major Depressive Disorder and Obsessive-Compulsive Disorder).

Q: Can Sostac cause headaches?

Yes. Headache is listed as a commonly reported undesirable effect in the official safety documents for Sostac, based on clinical trial findings.

Q: Is Sostac recommended for long-term management of a condition?

Official labels specify whether the drug is indicated for the acute treatment of symptoms or for maintenance therapy aimed at long-term management. Sostac is indicated for maintenance treatment for certain conditions.

Q: Do people report feeling 'foggy' on Sostac?

Official adverse event listings include reports of disturbances in attention and concentration. Regulatory warnings state that the medicine may affect a person's ability to think clearly, which may be related to the feeling described as 'foggy.'

Q: What does the term 'contraindication' mean in relation to Sostac?

A contraindication is defined in official patient information as a specific condition or factor that provides reason to withhold a medical treatment. This is based on safety data found in the official Prescribing Information.

Q: Is Sostac linked to any cardiovascular issues?

Official warnings and adverse event data include references to cardiovascular risks, such as changes in the electrical activity of the heart (QT interval prolongation).

Q: How is Sostac eliminated from the body?

Official pharmacokinetics data describes that the drug is metabolized by enzymes in the liver. It is then eliminated from the body primarily via excretion in the urine.

Q: What is the difference between Sostac and placebo in clinical trials?

Official clinical trial summaries report efficacy outcomes. This data demonstrates the difference in symptom improvement between patients receiving the active drug and those receiving an inactive placebo, providing the basis for regulatory approval.

Q: Is it true that Sostac has been researched for other conditions?

Yes. Government research bodies acknowledge that the medicine is sometimes used off-label or has been studied in research for conditions beyond its approved indications. This information is published in research updates and official databases.

Q: Does alcohol consumption change the way Sostac works?

Regulatory documents caution against the consumption of alcohol due to the potential for increased central nervous system (CNS) side effects, such as dizziness and drowsiness. Alcohol may also worsen the symptoms the drug is intended to treat.

Q: Is Sostac known to cause dry mouth?

Yes. Dry mouth (xerostomia) is listed as a commonly reported undesirable effect in the official safety documents for Sostac.

Q: What is the pregnancy risk category assigned to Sostac?

Official documentation provides the data used for assessing fetal risk. It was previously categorized under the U.S. FDA's Pregnancy Category C, which suggests the potential benefits may warrant use despite potential risks.

Q: Is Sostac a daily or as-needed medication?

Official documentation specifies the dosing frequency as 'once daily' for most forms, or 'once weekly' for delayed-release capsules. This defines it as a regularly scheduled medication for continuous use.

How should Sostac be stored and disposed of?

How to Store and Dispose of Sostac (Fluoxetine)

Storage and disposal of Sostac (fluoxetine) must follow specific regulatory conditions to maintain stability and ensure safety.

Storage Requirements

Condition Regulatory Requirement
Temperature Store at Controlled Room Temperature between 20 C and 25 C (68 F to 77 F).
Protection Keep the container closed tightly and protect the medicine from light.
Safety The product must be stored out of the sight and reach of children.

Disposal Instructions

Disposal of unused or expired Sostac should be managed via an authorized drug take-back program. If a program is unavailable, the medicine must be discarded by mixing it with an undesirable substance (e.g., used coffee grounds) and sealing the mixture in a bag before placing it in the household trash. The medication must not be flushed down a toilet or poured down a sink.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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