Cimetidine

TAGAMET

Open Cimetidine in the interactive console ↗

Pronunciation: sye-MET-i-deen

Cimetidine ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Cimetidine ballicule

Cimetidine TAGAMET mascot mnemonic cartoon — Visual mnemonic: Cimetidine mascot
**“Cy, Tag a Met”**
Cimetidine (left) increases levels of metformin (Mr Met, right)

What it isH2 receptor antagonist suppressing gastric acid; GERD and ulcer disease.

Why this oneIts antiandrogen action can cause gynecomastia, a peculiar liability not shared by famotidine.

What limits itInhibits multiple CYP enzymes and tubular creatinine secretion, creating interactions and a false creatinine rise; famotidine has replaced it.

Cimetidine molecular structure (skeletal formula) — Molecular structure: Cimetidine

Cimetidine prescription history

Animated chart of estimated U.S. prescriptions per year, Acid-suppressing meds (1977–2026). Cimetidine enters in 1977 (estimated).

FDA-approved for

ulcers (1977)

Principal riskInhibits four CYP enzymes; famotidine has replaced it

Classes and tags

Clinical profile

Therapeutic safety burden1 / 4

Overdose danger1 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk1 / 4

Legacy pregnancy categoryB

Defining liabilityLong-term infection, magnesium/B12 and bone risks; selected agents have clinically important CYP interactions.

FDA label

Read the full label on DailyMed ↗

NO BOXED WARNINGS

FDA dosing	Population	Start	Target	Max
Heartburn relief (OTC)	Adults & children ≥12 yr	200 mg (1 tablet) with water PRN	200 mg PRN	2 tablets/24h
Heartburn prevention (OTC)	Adults & children ≥12 yr	200 mg (1 tablet) up to 30 min before trigger food/drink	200 mg PRN	2 tablets/24h

Renal Undefined

Hepatic Undefined

Instructions

Swallow 1 tablet with a glass of water
For prevention, take right before or up to 30 minutes before eating/drinking trigger foods
Do not take more than 2 tablets in 24 hours
Children under 12 years: ask a doctor

Available strengths

tab 200, 300, 400, 800 mg
sol 300 mg/5 mL

Pregnancy Undefined

Lactation Undefined

Cost

Cimetidine (TAGAMET)

What pharmacies pay · NADAC 9/30/26

Strength		#/mo	generic $/unit	CostPlus
200 mg	tab	per unit	$0.20/ea	not offered
300 mg	tab	per unit	$0.24/ea	offered
400 mg	tab	per unit	$0.32/ea	offered
800 mg	tab	per unit	$0.72/ea	offered

Generic entry1994

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Memory aids: interaction avatars

CYP1A2 inhibitor (moderate)

CYP2C19 inhibitor (moderate)

CYP3A4 inhibitor (weak)

OCT2/MATE1 inhibitor

Open Cimetidine in the interactive console ↗

Self-check

Why can cimetidine cause a false creatinine rise?
Inhibits tubular creatinine secretion.
Which endocrine adverse effect distinguishes cimetidine from famotidine?
Gynecomastia from antiandrogen action.