Indacin

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Medically reviewed

Marina Burgos

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 Indacin

Property Description
Active ingredient Indometacin (Indomethacin)
Pharmacological class Nonsteroidal Anti-inflammatory Drug (NSAID)
Origin Synthetic (Indole derivative)
Routes of administration Oral, Rectal, Intravenous, Topical
General purpose Reducing inflammation, pain, and fever

Indacin: Definition, Active Ingredient, and Origin

Indacin is a commercial medicine containing the active ingredient Indometacin (or Indomethacin), a potent synthetic indole derivative. This medicine is consistently presented as a single-ingredient, prescription-only product. Indometacin is globally recognized as an established compound, supported by pharmacological studies for its efficacy in inflammatory conditions. The drug’s identity is founded upon this high-potency synthetic chemical base, combined with standard pharmaceutical bases to create the final preparation.

What Pharmacological Class Does Indacin Belong To?

Indacin belongs to the therapeutic group known as a Nonsteroidal Anti-inflammatory Drug (NSAID). Indometacin is noted for its powerful action as a prostaglandin synthesis inhibitor, giving it a robust profile compared to some milder NSAIDs. As an inhibitor of cyclooxygenase, which is necessary for prostaglandin synthesis, Indometacin works to reduce inflammation. This pharmacological strength ensures its therapeutic effectiveness where simultaneous reduction of inflammation, relief of severe pain (analgesic effect), and control of elevated fever (antipyretic effect) are required.

Available Preparations and Physical Forms

The active ingredient Indometacin is formulated in diverse physical forms to support various routes of administration, which is a key distinguishing feature of this compound. These preparations include standard oral forms such as capsules and tablets, as well as specialized formats including suppositories, solutions for intravenous injection, and topical preparations. This comprehensive range ensures the ability to deliver the anti-inflammatory and pain-relieving effects either throughout the body for systemic management or locally via topical applications.

Regulatory References

  1. Indomethacin - StatPearls - NIH

What side effects are possible with Indacin?

Possible Side Effects and Safety Information

The official safety information for Indacin (Indomethacin) is structured to highlight serious risks and common adverse reactions as determined by regulatory agencies.

Serious and Clinically Significant Risks

Indacin carries mandated warnings for potentially fatal events related to the cardiovascular and gastrointestinal systems. These include an increased risk for serious cardiovascular thrombotic events, such as myocardial infarction and stroke, which may be more likely with longer use. There is also a risk for serious gastrointestinal adverse events, including bleeding, ulceration, and perforation of the stomach or intestines, which can occur without warning symptoms.

Other serious risks include hepatotoxicity (liver damage), renal toxicity (kidney damage) that may lead to acute renal failure, hypertension, heart failure, and anaphylactic reactions.

Common Adverse Reactions

Adverse reactions reported in clinical studies with an incidence of 3% or more (Common) include headache, dizziness, dyspepsia (indigestion), and nausea.

Population-Specific Safety Considerations

  • Pregnancy: Use is generally avoided starting at 30 weeks gestation due to the risk of premature closure of the fetal ductus arteriosus.
  • Elderly Patients: This population has a greater risk for serious gastrointestinal adverse events and may be more susceptible to the drug's central nervous system effects.

Safety Restrictions and Limitations

Indacin is contraindicated (prohibited) for the treatment of peri-operative pain following coronary artery bypass graft (CABG) surgery and in patients with a history of asthma, urticaria, or allergic reactions after taking aspirin or other NSAIDs. The lowest effective dose should be used for the shortest duration consistent with individual patient goals to mitigate risk.

Overdose and Emergency Response

Overdose and When to Seek Help

Indacin (Indometacin) overdose is described in regulatory documents by a distinct profile of pronounced symptoms and severe potential outcomes. The documented clinical manifestations primarily involve the central nervous system (CNS) and the gastrointestinal (GI) tract. Initial signs may include severe headache, intense dizziness, mental confusion, profound drowsiness, and GI upset such as nausea, vomiting, and diarrhea.

Serious or life-threatening outcomes officially associated with substantial overdose include the risk of convulsions (seizures), progression to stupor or coma, acute renal failure, and severe GI events such as bleeding, ulceration, or perforation. The official regulatory labeling notes that elderly patients have an increased susceptibility to adverse reactions, necessitating particular care.

If an overdose is suspected, official guidance mandates that individuals seek immediate medical attention and contact emergency services or a Poison Control Center immediately. Management is strictly defined as symptomatic and supportive, as regulatory labeling confirms that no specific antidote is known. Documented procedures for clinical management focus on reducing absorption, which may include gastric lavage and administration of activated charcoal. Close observation, including continuous monitoring of vital signs and renal function, is required.

Therapeutic Uses of Indacin

What Indacin Treats: Main Uses and Benefits

Indacin (Indometacin) is applied across key therapeutic domains to provide symptomatic relief, primarily relevant for conditions presenting with symptoms of inflammation, pain, and fever. This medication is utilized in clinical settings where pronounced symptom manifestations disrupt daily stability, and where supportive symptom management is appropriate.


Key Therapeutic Applications

This medicine is commonly used for conditions characterized by episodic or fluctuating symptom patterns. These uses span the management of severe joint disorders, including Rheumatoid Arthritis, Ankylosing Spondylitis, and moderate to severe Osteoarthritis, as well as acute episodes like Gouty Arthritis, Tendinitis, and Bursitis. Furthermore, it is relevant in specialized contexts, such as certain severe headache syndromes and the management of Patent Ductus Arteriosus (PDA) in premature neonates.

“This medication is applied in scenarios where additional management of discomfort is required, helping patients cope more steadily with difficult manifestations.”

Quick Fact: Relief for Inflammatory Symptoms Indacin is generally applied to address symptom clusters that may become intense or disruptive, helping to ease the overall burden of joint swelling, tenderness, and chronic stiffness.


Benefits for Functional Stability

Indacin is used for managing the overall symptom load related to inflammatory or irritative states. By assisting with the reduction of chronic pain and addressing symptoms like morning stiffness that interfere with daily functioning, the supportive benefit contributes to improved day-to-day comfort and helps support functional stability when symptoms are more noticeable. It provides supportive relief during phases of increased distress or discomfort.

Regulatory References

  1. National Institutes of Health (NIH) StatPearls overview

Eligibility and Restrictions for Use

Who Can and Cannot Use Indacin?

Indacin (Indometacin) eligibility is strictly defined by regulatory authorities and depends on patient history, age, and physiological status.

Absolute Contraindications

Indacin is contraindicated (must not be used) in several populations. This includes patients with a known hypersensitivity to Indometacin or a history of allergic reactions to aspirin or other NSAIDs (Nonsteroidal Anti-inflammatory Drugs). It is also prohibited for patients with active peptic ulceration or gastrointestinal bleeding, as well as those with severe uncontrolled heart failure or in the setting of coronary artery bypass graft (CABG) surgery.

Age and Organ Function Restrictions

Safety and efficacy for oral and rectal formulations have not been established in children younger than 14 years of age. Use is contraindicated in patients with severe hepatic or severe renal impairment.

Population Eligibility Status (Regulatory Wording)
Third Trimester Pregnancy Contraindicated/Avoided
Breastfeeding Women Not Recommended/Avoided
Premature Neonates Permitted (IV only, for Patent Ductus Arteriosus)

Elderly patients are at greater risk for serious adverse events, necessitating caution and the lowest possible dose.

What should I know about interactions with other medicines?

Interactions with other medicines and products

The official regulatory profile for Indacin (Indometacin) outlines specific, documented interaction patterns with other medicines and substances, strictly based on government labeling.

Contraindicated and High-Risk Combinations

Co-administration with Diflunisal is formally prohibited due to an increased risk of serious gastrointestinal adverse events associated with increased Indometacin plasma levels. Indacin is also contraindicated for managing peri-operative pain in the setting of Coronary Artery Bypass Graft (CABG) surgery. The use of other NSAIDs or analgesic doses of Aspirin is generally not recommended due to an additive risk of gastrointestinal complications.

Exposure and Clearance Alterations

Indometacin reduces the renal clearance of Lithium, resulting in an elevation of plasma Lithium concentration. It similarly decreases the tubular secretion of Methotrexate, leading to potentiated toxicity. Indacin can also increase the serum concentration and prolong the half-life of Digoxin. Close monitoring is required when Indometacin is co-administered with Aminoglycosides in neonates due to the risk of elevated plasma levels.

Pharmacodynamic Interference

Co-administration with Antihypertensive Agents (including ACE inhibitors and ARBs) may diminish the antihypertensive effect. Similarly, Indometacin may reduce the natriuretic effect of Loop and Thiazide Diuretics. The risk of bleeding is increased when co-administered with Drugs that Interfere with Hemostasis, such as Warfarin or antiplatelet agents. The consumption of Alcohol is documented to increase the risk of stomach bleeding.

Population-Specific Cautions

The risk of deterioration of renal function with ACE Inhibitors/ARBs is noted as heightened in elderly, volume-depleted, or renally impaired patients.

Mechanism of Action

Indacin is an indole acetic acid derivative that functions as a nonselective inhibitor of cyclooxygenase (COX) enzymes, specifically targeting both COX-1 and COX-2 isoforms. . It binds to the active site of these enzymes, preventing the conversion of arachidonic acid into prostaglandins and thromboxanes, which are lipid-based signaling molecules.

This molecular interaction results in the downstream cascade of reduced prostaglandin synthesis across various tissues, including the central nervous system, renal vasculature, and peripheral sites. The system-level physiological consequence of this general reduction in prostanoid production is the modulation of cellular processes mediated by these local hormones, such as peripheral vasodilation, thermal set-point elevation in the hypothalamus, and afferent nerve sensitization. Indacin also affects the vascular smooth muscle tone in specific circuits, such as the cerebral vasculature, by mechanisms involving nitric oxide pathways and intracranial vasoconstriction. Additionally, Indacin can interfere with the migration of leukocytes to sites of stimulus and stabilize lysosomal membranes, further modulating cellular response pathways.

Dosage and Administration Information

The administration of Indacin (Indometacin) is structured around its diverse formulations to meet specific usage requirements, adhering to the principle of using the lowest effective dosage for the shortest duration necessary. The active ingredient is administered via oral forms (immediate-release and extended-release capsules, or suspension), rectal suppositories, and through intravenous infusion, which is reserved for specialized pediatric use.

For chronic conditions like arthritis, the standard adult oral dosing typically begins with 25 mg two or three times daily. This starting dose is subject to upward titration at weekly intervals by 25 mg or 50 mg, adjusting until a satisfactory level is achieved, but it must not exceed a maximum total daily dose of 200 mg for immediate-release preparations. To support absorption, oral capsules are generally instructed to be taken with food. The frequency is usually divided daily use.

A specific label instruction allows a larger portion of the total daily dose, up to 100 mg, to be administered at bedtime, leveraging the availability of rectal suppositories for this purpose. When used for acute conditions, such as gouty arthritis or acute painful shoulder, the total course of therapy is time-bound, often 7 to 14 days, and the regimen must be rapidly discontinued upon control of the acute episode. Special administration notes include the necessity to swallow extended-release capsules whole and the requirement for slow infusion over 20 to 30 minutes when the intravenous form is utilized.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Indacin

Evidence Overview for Chronic Inflammatory Joint Disorders

Research exploring Indacin in chronic conditions such as Rheumatoid Arthritis, Osteoarthritis, and Ankylosing Spondylitis relies heavily on a long history of clinical evaluation. The evidence landscape primarily includes Randomized Controlled Trials (RCTs) and systematic reviews that have compared Indacin against either a placebo or to an active comparator. These studies were conducted during periods of increased symptom activity in adult patients whose conditions are characterized by fluctuating or episodic manifestations.

Research Evidence for Acute Pain and Inflammatory Episodes

Indacin was studied for its application in conditions associated with acute or disruptive episodes, specifically focusing on short-term needs such as Acute Gouty Arthritis, Bursitis, and Tendinitis. This area of research is typically supported by short-term RCTs that observed responses over defined time intervals. Studies explored outcomes describing episodic or acute changes and measured the rate and extent of observed changes in acute pain levels.

Study Design for Specialized Indications (PDA and Headaches)

Indacin was evaluated in unique and specific research contexts. For instance, Randomized Controlled Trials (RCTs) and systematic reviews have been conducted in the neonatal intensive care setting for the evaluation for Patent Ductus Arteriosus (PDA) in premature infants. Separately, Indacin was studied for certain severe, rare headache syndromes, deriving evidence largely from case reports and diagnostic trials. Findings from these studies are specialized and results apply only to the populations studied.

Key Limitations and Areas of Research Uncertainty

The evidence base for Indacin was observed in various studies exploring symptom patterns, but several research limitations exist. Comparative evidence is lacking in some areas, particularly when assessing Indacin against the newest generation of pain and inflammation therapies. The certainty remains low regarding the full range of potential long-term effects, as follow-up durations were limited in many of the key trials. Furthermore, generalizing findings to all patient scenarios may introduce uncertainty.

Key Studies & References

  1. Indomethacin-responsive headache syndromes

Frequently Asked Questions (FAQ)

Common questions about Indacin (FAQ)

Q: How does Indacin differ from over-the-counter anti-inflammatory medicines?

Indacin is classified as a prescription-only Nonsteroidal Anti-inflammatory Drug (NSAID), distinguishing it from many over-the-counter pain and inflammation medicines. Official prescribing information indicates that Indacin is typically reserved for the management of moderate to severe conditions, such as specific forms of arthritis or acute gout. This classification is due to its potent mechanism of action and the risk profile associated with its use.

Q: Why would a doctor choose Indacin over other treatment options?

Regulatory data states that Indacin is a potent inhibitor of the body’s inflammatory response, reflecting its role in treating moderate to severe inflammatory conditions, as indicated in official documents. The drug's official profile supports its use based on the treating physician's assessment of the severity of the patient's condition and medical history.

Q: How long does it typically take for Indacin to start working?

After taking an oral dose, the medicine is readily absorbed and reaches its highest level in the bloodstream in approximately two hours. For short-term use in acute pain, patients may notice effects relatively quickly. However, when treating chronic conditions like arthritis, official information indicates that the full therapeutic benefit may take one to two weeks or longer to be achieved.

Q: What happens if Indacin is stopped suddenly?

For acute (short-term) conditions, official labeling advises rapid discontinuation once the episode is under control. However, when Indacin is used for chronic therapy, regulatory documents stress that patients should follow the treatment plan unless their healthcare provider instructs otherwise. Official guidance indicates that any changes to a long-term regimen are typically made under the direction of a healthcare professional.

Q: Are there different strengths of Indacin available?

According to official regulatory sources, Indacin is available in different strengths and types of formulations to meet various treatment needs. These include standard immediate-release capsules, extended-release capsules, and rectal suppositories. The selection of the appropriate form and strength is determined during the prescribing process.

Q: Is Indacin considered a long-term treatment option?

Indacin is officially approved for the management of chronic conditions, but regulatory warnings must be considered. Studies and official information indicate that the risk of serious side effects, such as severe gastrointestinal bleeding, may increase the longer the medicine is used. The regulatory documents specify that the lowest effective dosage should be used for the shortest duration consistent with treatment goals to help mitigate risk.

Q: Is it okay to store Indacin in the bathroom medicine cabinet?

Official handling and storage instructions require that oral forms of Indacin be stored in a tightly closed container at a controlled room temperature, away from both heat and moisture. Because the bathroom medicine cabinet often involves significant humidity and temperature fluctuations, this environment may compromise the stability of the medicine.

Q: Can Indacin be crushed or split?

Official patient information states that extended-release capsules must be swallowed whole and should not be opened, crushed, broken, or chewed. Altering the extended-release formula can impact how the drug works in the body. Questions regarding the alteration of other forms of the medicine can be clarified by reviewing the specific product instructions or speaking with a pharmacist.

Q: Are there specific food items or beverages that interact with Indacin?

Official drug labeling notes that alcohol consumption may increase the risk of stomach bleeding while using Indacin. Official information states that alcohol use should be discussed with a healthcare provider. Aside from general advice to take oral forms with food, no other common food items or non-alcoholic beverages are listed as strictly contraindicated.

Q: How do regulatory bodies define the 'serious' side effects of Indacin?

A serious adverse event, as defined by regulatory standards (such as the FDA), is one that results in severe outcomes like death, a life-threatening situation, inpatient hospitalization, or permanent disability. Official documents highlight these risks so that patients are aware of the most clinically significant safety information.

Q: What official documents describe the proper way to handle Indacin?

Official instructions for the proper handling of Indacin are contained in several authorized documents. These include the FDA Prescribing Information, the Patient Information Leaflet or Medication Guide dispensed with the prescription, and public resources like DailyMed. These documents detail the appropriate way to store, administer, and dispose of the drug.

Q: What is the general guidance on stopping Indacin?

The general guidance provided in official patient information is to follow the medicine schedule exactly as prescribed by the healthcare team. Any changes to a patient's regimen are typically addressed in consultation with a medical professional.

Q: Does Indacin affect mental clarity or focus?

Official adverse event reports for Indacin include headache and dizziness. Official labeling advises against driving or operating machinery until the patient is aware of the drug’s potential effect on their alertness and coordination.

Q: What is the expected duration of action for Indacin?

Studies on the drug's effects indicate that the mean half-life of Indacin is estimated to be approximately 4.5 hours, meaning half of the drug is eliminated from the system in that time. When taken regularly, steady-state concentrations, which are consistent levels in the body, are usually achieved.

Q: If I miss a dose of Indacin, what are the official instructions?

According to official patient information, if a dose is missed, the patient should take it as soon as they remember. Regulatory documents specify that if it is almost time for the next scheduled dose, the missed dose should be skipped, and the regular dosing schedule should be resumed. Official guidance includes the instruction not to take a double dose to compensate for the missed one.

Q: What happens if I accidentally take more Indacin than intended?

Official regulatory documents warn that taking more Indacin than intended can lead to an overdose, potentially causing symptoms such as severe headache, confusion, nausea, vomiting, and seizures. In the event an overdose is suspected, contact with emergency medical services or a Poison Control Center is necessary.

Q: Can I take Indacin if I use vitamins or supplements?

Official regulatory documents specify that patients should inform their healthcare provider about all vitamins, supplements, and herbal products they currently use. Specific interactions are noted for supplements containing high levels of potassium or certain herbs like ginkgo biloba, which may increase bleeding risk.

Q: What is the process for monitoring a patient while they are on Indacin?

According to official prescribing information, patients taking Indacin are monitored for several potential changes. This typically involves checking for changes in blood pressure, signs of fluid retention (edema), and symptoms of liver or gastrointestinal toxicity. Blood and urine tests may also be conducted to assess kidney and liver function.

Q: Does Indacin cause drowsiness?

Official adverse reaction lists for Indacin do not include drowsiness among the most common reactions, but reports of excessive sleepiness have been noted, particularly in cases of higher doses or overdose. Official labeling states the drug can affect alertness and caution is warranted until the patient is aware of the drug’s effects.

Q: Is Indacin available as a generic medicine?

Yes, the active ingredient, Indometacin, has been approved by regulatory bodies like the FDA for generic versions. The availability of a specific generic formulation of the medicine depends on the product strength and form.

Q: Can Indacin affect the results of lab tests?

Studies and official product information indicate that Indacin can affect the results of certain lab tests. It can increase the plasma concentrations of other drugs, such as Lithium, and may also interfere with platelet function and kidney function markers that are evaluated through routine blood and urine tests.

How should Indacin be stored and disposed of?

Storage Conditions

Indacin capsules must be stored at Controlled Room Temperature, officially defined as 20 C to 25 C (68 F to 77 F). The medication requires protection from both light and moisture, and the container must be kept tightly closed to maintain stability. The oral suspension must be stored below 30 C (86 F) and must not be frozen.

Rectal suppositories require refrigeration, stored between 2 C and 8 C (36 F and 46 F). If a suppository softens, it may be chilled briefly in the refrigerator or under cold water before insertion.

Handling and Disposal

All forms of this medication must be stored out of the reach of children. For disposal, unused or expired Indacin must be discarded according to official instructions. This often involves utilizing a medicine take-back program or following authorized household disposal guidelines, such as mixing the product with an undesirable substance before discarding in the trash.

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

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