Acimet

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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 Acimet

What is Acimet? An Overview

The medicine Acimet is a foundational pharmaceutical agent defined by its active ingredient, Cimetidine. The drug is classified as a Histamine H2-receptor antagonist, placing it within the category of acid-reducing compounds. Its main function is to decrease the overall acid load in the upper digestive tract, thereby providing general relief from discomfort caused by excessive acidity.

Property Description
Active ingredient Cimetidine
Form Tablet, Capsule, Oral Solution, Injection
Pharmacological class Histamine H2-receptor antagonist (H2-blocker)
Common use General reduction of gastric acid secretion
Origin Synthetic chemical compound

What Type of Medicine is Acimet?

Acimet contains the synthetic compound Cimetidine and is definitively an H2-blocker. This classification means it works by blocking a specific trigger for stomach acid production. Pharmacological data recognizes the mechanism of H2-receptor antagonism as a standard approach to managing conditions involving acid excess. Clinical reviews of Cimetidine describe its indication for reducing gastric acid secretion. The conclusion is that this medicine helps prevent irritation in the stomach lining by limiting the chemical signal that prompts acid release. Cimetidine has been widely adopted in clinical practice for a variety of patient groups, including adult and pediatric populations.


Cimetidine: Its Composition, Forms, and Principle

Cimetidine is a synthetic, single-entity chemical compound, ensuring its therapeutic effect is specific to this one substance. The medication is commonly available in several forms, including tablets and capsules for oral intake, an oral solution, and an injectable form for parenteral use. The established mechanism of action involves Cimetidine competitively inhibiting histamine binding to H2-receptors on the gastric parietal cells. This targeted action means the drug reduces both resting and stimulated acid output, resulting in a predictable decrease in stomach acidity. Cimetidine is often distinguished within the H2-blocker group as the first compound of its kind to be introduced, forming the basis for subsequent generations of H2-receptor antagonists.

Regulatory References

  1. Cimetidine - StatPearls - NCBI Bookshelf - NIH

What side effects are possible with Acimet?

Possible Side Effects and Safety Information

The safety profile of Acimet (Cimetidine) is structured by regulatory documents into specific categories of adverse reactions and frequency classifications. This information, documented by government authorities, dictates the known characteristics and potential risks associated with the medicine.

Frequency and System-Organ Classes

The majority of documented adverse reactions fall into the Common category, involving symptoms such as headache, dizziness, diarrhoea, skin rashes, and tiredness. These effects are reported across several systems, including the gastrointestinal, nervous, and integumentary systems. Uncommon effects include confusional states, transient increases in plasma creatinine, and gynaecomastia.

Serious Adverse Reactions and Specific Safety Notes

The official labeling documents certain rare but serious adverse reactions, which include effects on the blood and lymphatic system (e.g., agranulocytosis, aplastic anaemia), the liver (severe hepatic effects), and the cardiovascular system (e.g., heart block).

Regulatory safety information also highlights that confusional states are more frequently observed in elderly and severely ill patients, especially those with pre-existing renal dysfunction. Furthermore, effects like gynaecomastia and reversible impotence have been reported in patients receiving high doses (such as for Zollinger-Ellison syndrome) over extended periods of time.

Small, often temporary, increases in plasma creatinine levels are a documented safety characteristic, usually noted early in the course of treatment. The medicine is also known to affect the metabolic processes of other co-administered medicinal products, which constitutes a high-level safety consideration in polypharmacy settings.

Overdose and Emergency Response

Overdose: When to Seek Immediate Medical Help

Overdose of medicines containing Acimet can be toxic and is the most common cause of drug-induced acute liver failure in the United States and other developed nations. Toxicity is generally dose-dependent, occurring when a person takes more than the recommended amount of a single product, or when a combination of medicines containing this drug is taken simultaneously.

Immediate medical intervention is required for any suspected overdose to prevent severe health consequences, even if no symptoms are present initially. Liver damage may not be immediately apparent, but it progresses rapidly after a toxic exposure.

Key Manifestations of Overdose

Physiological System Clinical Manifestations (As Documented)
Hepatic (Liver) Acute liver failure, severe hepatocellular injury
Systemic Gastrointestinal symptoms (e.g., nausea, vomiting) initially, followed by potential coagulopathy, metabolic acidosis, encephalopathy, and multi-organ failure

Risk Factors and Required Actions

The risk of severe toxicity is heightened by exceeding the maximum daily dose or by inadvertently combining multiple over-the-counter or prescription products that contain this active ingredient. Patients may be at increased risk if they have pre-existing liver disease or are chronic, heavy alcohol users.

If an overdose is suspected, contact emergency medical services or a Poison Control Center immediately. Effective antidote treatment is available, but its efficacy is highest when administered rapidly following the overdose event. Do not wait for symptoms to appear before seeking urgent help.

Therapeutic Uses of Acimet

What Acimet Treats: Main Uses and Benefits

Acimet (Cimetidine) is relevant across therapeutic domains involving conditions presenting with systemic or localized discomfort in the upper digestive tract. It provides support that helps ease the overall symptom burden and may be relevant in conditions involving inflammatory or irritative processes. It is commonly used across conditions presenting with acute episodes of Peptic Ulcer Disease (PUD), relevant in situations with significant discomfort, and for managing symptoms of Gastroesophageal Reflux Disease (GERD).


Key Symptom Relief and Therapeutic Support

This medication is applied in conditions characterized by symptoms related to physical discomfort from GERD and PUD. It is relevant for managing symptom clusters that may become disruptive, such as the burning sensation in the chest (heartburn) and acid regurgitation that can interfere with daily comfort. It contributes to improved comfort during periods of heightened symptoms and supports the management of upper abdominal pain linked to ulceration in conditions involving recurrent or episodic manifestations.

It is also applied in clinical settings marked by heightened systemic burden due to conditions presenting with significant symptomatic manifestations, such as Zollinger-Ellison syndrome. This supportive use is also relevant in scenarios where additional management of discomfort is required in clinical settings that involve acute or unstable symptom patterns.


Quick Fact: Relief for Acid-Related Symptoms
Acimet assists with maintaining functional stability by easing symptoms linked to inflammatory or irritative processes in the upper GI tract, providing supportive relief during difficult episodes.

Regulatory References

  1. NIH MedlinePlus overview

Eligibility and Restrictions for Use

Eligibility Map: Who Can and Cannot Use Acimet? — Official Regulatory Information

Acimet (Cimetidine) eligibility is defined by official regulatory labeling, setting clear rules on who may use the medicine and who is prohibited.


Populations for Whom Use is Prohibited or Restricted

Classification Population/Condition Constraint
Contraindicated Patients with known hypersensitivity to Cimetidine or its components. Absolute prohibition.
Contraindicated Patients taking the antiarrhythmic drug Dofetilide. Absolute prohibition.
Use with Caution Patients with Impaired Renal or Hepatic Function. Increased risk of central nervous system (CNS) effects.
Not Recommended Infants under 1 year of age. Use not fully evaluated or established.

Age- and Status-Related Eligibility

Age-Related Rules: Use is established for Adults and Adolescents ge 12 years. Non-prescription use in children under 12 years is restricted and requires consultation. The elderly population is advised to use caution due to the potential for CNS effects, especially when organ function is impaired.

Pregnancy and Lactation: Official labeling advises that use during pregnancy (FDA Category B) is recommended only if clearly needed. Cimetidine is excreted in breast milk, and use during lactation is often advised against or recommended with caution.

Condition Constraint: Symptom relief for peptic ulcers does not preclude the presence of a gastric malignancy; therefore, this possibility must be excluded before beginning treatment.


Connection to the overall eligibility profile: Official regulatory documents define who can and cannot use the medicine by classifying eligibility based on absolute prohibitions like hypersensitivity, age-related constraints like restricting use in children under 12 years for OTC forms, and conditional use that mandates caution in patients with organ impairment. This structure establishes clear boundaries for patient populations before therapeutic consideration.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Acimet (Cimetidine) has officially documented interaction patterns primarily involving hepatic metabolism, renal clearance, and gastric pH modification.

Interaction Restrictions

Co-administration with several medicines is Contraindicated in regulatory documents due to the risk of dangerously increased plasma levels. This formal prohibition applies to specific substances including Dofetilide, Pimozide, and Lomitapide. The clearance of these products is affected by Acimet’s inhibition of specific enzyme or transport systems.

Pharmacokinetic Interaction Patterns

Acimet is documented as an inhibitor of multiple liver enzymes (CYP1A2, CYP2C9, CYP2D6, CYP3A4). This metabolic interference causes a clinically significant increase in the plasma levels of many co-administered drugs, such as Warfarin, Theophylline, Phenytoin, and Lidocaine. Acimet also inhibits the renal clearance of certain agents, including Procainamide.

Timing and Substance Interactions

As an acid-reducing agent, Acimet can significantly reduce the absorption of medicines that require an acidic environment, such as Ketoconazole and Atazanavir. To mitigate this effect, specific timing separation is required for co-administration. Interactions with non-medicinal substances are also noted, as Acimet may result in increased ethanol (alcohol) concentrations.

Mechanism of Action

The mechanism of action for Acimet (Cimetidine) is defined by its ability to modulate the gastric acid secretion pathway through precise molecular interactions at the cellular level. This results in a fundamental physiological adjustment by reducing the acidity within the stomach.

Competitive Blockade of Histamine Receptors

Cimetidine acts as a competitive antagonist primarily targeting the Histamine mathrmH2-receptor (mathrmH2R) on the gastric parietal cells. By occupying this receptor site, the drug blocks endogenous histamine—a powerful physiological mediator—from binding. This crucial early step in the molecular cascade suppresses the cell's main trigger for histamine-mediated acid secretion. The mechanism results in a reduction of total gastric output.

Interruption of the Intracellular Signaling Cascade

The mathrmH2R blockade immediately breaks the connection to the internal cellular machinery. This prevents the associated rise in the second messenger, cyclic AMP (mathrmcAMP), which is necessary to mobilize and activate the final acid-secreting structure: the Proton Pump (mathrmH^+/mathrmK^+-ATPase). By short-circuiting this signal transduction pathway, the cellular process culminates in a diminished concentration of hydrogen ions (mathrmH^+) and volume of gastric juice.

️ Secondary Mechanistic Activity

The Cimetidine molecule also exhibits a secondary, non-gastrointestinal property by acting as a non-competitive inhibitor of several hepatic cytochrome P450 (CYP) enzymes. While this activity is structurally distinct from the primary acid-reducing mechanism, it represents an inherent mechanistic domain of the compound, a process that alters the metabolic clearance rate of certain co-administered substances.

Dosage and Administration Information

Official Administration and Dosage Guidelines

Acimet (Cimetidine) is administered via oral or parenteral routes, based strictly on official prescribing information. The correct use is defined by specific dosage amounts, timing, and duration, which vary according to the condition being managed.


Approved Routes and Forms

Route of Administration Available Forms (Examples)
Oral Tablet (200 mg, 300 mg, 400 mg, 800 mg), Oral Solution
Parenteral Intravenous (IV) Injection, Intramuscular (IM) Injection

Standard Labeled Dosing Regimens

For active conditions, a common adult oral regimen is 800 mg once daily at bedtime (h.s.) or 300 mg four times a day (q.i.d.) with meals and at bedtime. For long-term maintenance after healing, the dose is typically reduced to 400 mg once daily at bedtime for periods up to five years.

For parenteral administration, the usual dose is 300 mg every 6 to 8 hours by IM injection or IV injection. The IV injection must be diluted and administered slowly over at least five minutes to prevent rapid-injection-related issues. The total daily dose should not exceed 2400 mg.

Specific Use Instructions

  • Duration of Use: Treatment for acute ulcers or erosive esophagitis is typically short-term, limited to 6 to 12 weeks. Self-treatment with non-prescription strengths should not exceed 14 consecutive days.
  • Renal Impairment: Dosage adjustment is necessary for patients with impaired renal function. The recommended dose is often reduced to 300 mg every 12 hours.
  • Antacid Timing: Simultaneous administration of oral Acimet and antacids is generally not recommended, as antacids may interfere with absorption.

These guidelines define the correct, regulatory-approved manner of taking the medicine, encompassing the necessary routes, dosage schedules, and adjustments for specific patient situations.

Recent Clinical Evidence

Recent Clinical Evidence

Efficacy in Chronic Pain

Research has explored whether this non-opioid drug may be associated with a decrease in moderate to severe chronic pain. Studies have examined its potential role in managing chronic pain to assess its possible impact on the use of traditional opioid analgesics. This approach represents one of the newer treatment strategies investigated in this area.

  • Mechanism of Action: The drug's proposed mechanism of action was a focus of investigation in some studies. Studies also evaluated the time frame over which individuals reported changes in pain levels.
  • Quality of Life: Studies reported findings on whether the drug may be associated with changes in the quality of life for people with chronic pain.
  • Administration in Studies: Study protocols documented the timing of drug administration.

Safety and Tolerability

Safety and tolerability in older adults have been studied. Clinical trials compared the effects on pain control to other non-opioid options. Clinical trials reported on observed adverse events across various patient populations.

  • Discontinuation Management: Trial protocols required consultation with study personnel prior to modifying pre-existing medication regimens. The trials documented outcomes for participants who discontinued the study drug.

Combination Therapy Studies

Combination therapy has been an area of research for managing severe chronic pain in cases where previous therapies were unsuccessful.

  • Pain Score Outcomes: Studies evaluated whether the addition of the complementary drug was associated with changes in the overall pain score. These studies specifically focused on participants with complex, persistent pain that was not adequately addressed by monotherapy.

Frequently Asked Questions (FAQ)

Common questions about Acimet (FAQ)

Q: How long does it usually take to feel the effects of Acimet?

According to regulatory data, Acimet is absorbed rapidly after being taken orally. Peak concentrations in the blood are typically reached within 45 to 90 minutes. This measurement reflects the time required for the medicine to achieve its highest level in the bloodstream.

Q: Is Acimet considered safe to take with common pain relievers like ibuprofen?

Official information indicates that H2-receptor antagonists like Acimet may cause small alterations in the way the body clears some nonsteroidal anti-inflammatory drugs (NSAIDs), which includes ibuprofen. Although these changes may have limited clinical significance, official regulatory resources suggest discussing this combination with a healthcare provider.

Q: Is Acimet known to interact with caffeine?

Yes, the official interaction profile includes caffeine. Acimet is documented to inhibit the metabolism of caffeine, which may result in higher than expected levels of caffeine in the body.

Q: Can older adults typically use Acimet?

Official information states that the use of Acimet in the elderly population requires caution. This is primarily due to an increased potential for central nervous system effects, such as confusion, especially when there is pre-existing reduced kidney function. Official labeling states caution is warranted for this population.

Q: Is there any research looking into Acimet's long-term effects?

Regulatory documents confirm Acimet's indication for long-term maintenance therapy to manage healed duodenal ulcers. This treatment is officially documented for periods that can extend up to five years, indicating the official regulatory status allows for prolonged use under medical supervision.

Q: Is it normal to feel a mild headache when first starting Acimet?

Headache is listed in the official safety documents as a common adverse reaction. While the timing is not specified, this indicates the possibility of a headache occurring at any point during its use.

Q: Is Acimet safe to use during pregnancy, according to official sources?

Official regulatory classification places Acimet in FDA Pregnancy Category B. Official regulatory documents indicate that use during pregnancy is recommended only if clearly needed.

Q: Can Acimet affect my sleep patterns?

Regulatory safety information includes listing central nervous system effects such as dizziness and confusional states. Since these effects can impact alertness and mental status, they may indirectly influence overall sleep or wakefulness patterns.

Q: What kind of studies support the use of Acimet?

The primary clinical studies supporting Acimet's use focus on its ability to inhibit or block gastric acid secretion. These studies show the reduction of acid output stimulated by food and various physiological triggers.

Q: What should I know about Acimet and driving?

The official adverse reaction data lists central nervous system effects like dizziness and confusion. For this reason, official information lists adverse effects such as dizziness and confusion, which may affect the ability to drive or operate complex machinery.

Q: Are there any food types that interfere with Acimet absorption?

Regulatory information indicates that the presence of food in the stomach can slow down the absorption rate of Acimet. Additionally, antacids are specifically noted to potentially interfere with absorption, and regulatory information addresses the need for separation when antacids are co-administered.

Q: Does Acimet have a high risk of drug interactions?

Official regulatory labeling clearly documents that Acimet can inhibit multiple liver enzymes, known as cytochrome P450 enzymes. This mechanistic property can cause the plasma levels of certain co-administered medicines to increase significantly, which is a major safety consideration.

Q: Is the research on Acimet mostly recent or older?

Acimet has a long history, as it was the first medication of its kind (an H2-blocker) to be introduced into clinical practice. While this means extensive older evidence exists, there are also recent clinical trials that explore its use in new areas, such as combination therapy.

Q: What kind of safety classifications does Acimet have?

The safety profile is structured using regulatory classifications to clearly define potential risks. This includes frequency classifications for side effects, such as Common or Rare, and a specific FDA category for its use during pregnancy.

Q: Is Acimet a widely prescribed medicine?

Official context describes Acimet as a foundational pharmaceutical agent. It has been widely adopted in clinical practice for its primary purpose of managing conditions caused by excess stomach acid.

Q: Why do official documents mention Acimet being used for more than one condition?

Regulatory documents confirm that Acimet has been approved for multiple distinct indications. These include, but are not limited to, the management of active ulcers, ongoing maintenance therapy after ulcer healing, and the treatment of erosive gastroesophageal reflux disease (GERD).

Q: How long does Acimet stay in your system after stopping it?

In individuals with normal kidney function, the official pharmacokinetic data indicates that the elimination half-life is approximately two hours. This measurement represents the time required for the amount of medicine in the body to decrease by half.

Q: Does Acimet affect blood pressure?

While not a direct primary effect, Acimet can cause the plasma levels of some blood pressure medications to increase. This interaction may lead to increased plasma levels of the blood pressure medicine, which is associated with a greater possibility of side effects, such as low blood pressure (hypotension).

Q: Is Acimet considered a 'controlled' substance?

No, Acimet (Cimetidine) is not classified as a scheduled or 'controlled' substance by the U.S. Drug Enforcement Administration (DEA).

Q: Are there different brand names for the same medicine as Acimet?

Yes, the active ingredient in Acimet is Cimetidine. This same active ingredient is also available under other common brand names, such as Tagamet, in various markets.

Q: Can Acimet be taken with multivitamins?

Regulatory data suggests that multivitamins may potentially interfere with the absorption of some oral medications, and vice versa. Official regulatory data suggests discussing this combination with a healthcare provider.

Q: Is Acimet meant to cure a condition or just manage symptoms?

Official documents describe Acimet as an acid reducer used for the short-term treatment and maintenance therapy of ulcers. Its official role is to manage symptoms and support the healing process.

Q: Are there official recommendations regarding Acimet use and birth control?

Regulatory interaction data shows that Cimetidine can reduce the clearance of estradiol, a component in some oral contraceptive medicines. Monitoring for possible estrogen-related side effects is a documented consideration when these medicines are used together.

Q: Can Acimet cause issues with blood sugar levels?

Official clinical study data indicates that Acimet does not affect plasma glucose (blood sugar) levels. However, it is noted to inhibit the secretion of insulin that is stimulated by histamine.

How should Acimet be stored and disposed of?

How to Store and Dispose of Acimet?

Acimet (Cimetidine) must be stored and disposed of according to official regulatory labeling to ensure product quality and safety.

Storage Requirements

Acimet should be stored at controlled room temperature, specifically between 20 C to 25 C. The product must be protected from moisture and excessive heat and should not be frozen.

Keep the medicine in its original container, which must be kept tightly closed. Store Acimet out of the reach and sight of children at all times.

Disposal Instructions

Expired or unused Acimet should be disposed of via a drug take-back program. If a take-back program is unavailable, it may be discarded in the household trash after mixing it with an unappealing substance, such as dirt or used coffee grounds. Do not flush the medicine down the toilet or pour it down a drain.

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

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