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Tagamet Side Effects Center
Medical Editor: John P. Cunha, DO, FACOEP
Tagamet (cimetidine) is a histamine receptor antagonist used to treat and prevent certain types of ulcer, and to treat conditions that cause the stomach to produce too much acid. It is also used to treat gastroesophageal reflux disease (GERD), when stomach acid backs up into the esophagus and causes heartburn. Tagamet is available in generic form. Common side effects of Tagamet include headache, dizziness, drowsiness, depression, agitation, breast swelling or tenderness (in men), joint or muscle pain, skin rash, diarrhea, nausea, or constipation.
Dose of Tagamet depends on the condition being treated and the patient's response to the medication. Tagamet may interact with blood thinners, clopidogrel, phenytoin, nifedipine, metronidazole, propranolol, chlordiazepoxide, lidocaine, diazepam, theophylline, depression or anxiety medications. Tell your doctor all medications you use. Tagamet should be used only when prescribed during pregnancy. This medication passes into breast milk. Consult your doctor before breast-feeding.
Our Tagamet (cimetidine) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What is Patient Information in Detail?
Easy-to-read and understand detailed drug information and pill images for the patient or caregiver from Cerner Multum.
Tagamet in Detail - Patient Information: Side Effects
Stop using cimetidine and get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have any of these serious side effects:
- cough, fever, chest congestion, trouble breathing;
- red or blistering skin rash;
- jaundice (yellowing of the skin or eyes);
- easy bruising or bleeding, unusual weakness;
- feeling faint, light-headed, disoriented, or confused;
- urinating less than usual;
- irregular heartbeat; or
- a rash.
Less serious side effects may include:
- feeling dizzy, depressed, or agitated;
- breast swelling or tenderness (in men);
- joint or muscle pain;
- mild skin rash;
- headache; or
- diarrhea, nausea, or constipation.
Read the entire detailed patient monograph for Tagamet (Cimetidine)
What is Patient Information Overview?
A concise overview of the drug for the patient or caregiver from First DataBank.
Tagamet Overview - Patient Information: Side Effects
If your doctor has directed you to use this medication, remember that he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor immediately if any of these unlikely but serious side effects occur: mental/mood changes (e.g., agitation, confusion, depression, hallucinations), trouble urinating, muscle/joint pain, breast swelling/soreness in males, decreased sexual ability (with very high doses of this medication).
Tell your doctor immediately if any of these rare but very serious side effects occur: easy bruising/bleeding, signs of infection (e.g., fever, persistent sore throat, cough, trouble breathing), fast/slow/irregular heartbeat, unusual tiredness, persistent nausea/vomiting, severe stomach/abdominal pain, dark urine, yellowing eyes/skin, change in the amount of urine.
A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Read the entire patient information overview for Tagamet (Cimetidine)
What is Prescribing information?
The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.
Tagamet FDA Prescribing Information: Side Effects
Adverse effects reported in patients taking Tagamet (cimetidine) are described below by body system. Incidence figures of 1 in 100 and greater are generally derived from controlled clinical studies.
Diarrhea (usually mild) has been reported in approximately 1 in 100 patients.
Headaches, ranging from mild to severe, have been reported in 3.5% of 924 patients taking 1600 mg/day, 2.1% of 2,225 patients taking 800 mg/day and 2.3% of 1,897 patients taking placebo. Dizziness and somnolence (usually mild) have been reported in approximately 1 in 100 patients on either 1600 mg/day or 800 mg/day.
Reversible confusional states, e.g., mental confusion, agitation, psychosis, depression, anxiety, hallucinations, disorientation, have been reported predominantly, but not exclusively, in severely ill patients. They have usually developed within 2 to 3 days of initiation of Tagamet (cimetidine) therapy and have cleared within 3 to 4 days of discontinuation of the drug.
Gynecomastia has been reported in patients treated for 1 month or longer. In patients being treated for pathological hypersecretory states, this occurred in about 4% of cases while in all others the incidence was 0.3% to 1% in various studies. No evidence of induced endocrine dysfunction was found, and the condition remained unchanged or returned toward normal with continuing Tagamet (cimetidine) treatment.
Reversible impotence has been reported in patients with pathological hypersecretory disorders, e.g., Zollinger-Ellison Syndrome, receiving Tagamet (cimetidine) , particularly in high doses, for at least 12 months (range 12 to 79 months, mean 38 months). However, in large-scale surveillance studies at regular dosage, the incidence has not exceeded that commonly reported in the general population.
Decreased white blood cell counts in Tagamet (cimetidine) -treated patients (approximately 1 per 100,000 patients), including agranulocytosis (approximately 3 per million patients), have been reported, including a few reports of recurrence on rechallenge. Most of these reports were in patients who had serious concomitant illnesses and received drugs and/or treatment known to produce neutropenia. Thrombocytopenia (approximately 3 per million patients) and, very rarely, cases of pancytopenia or aplastic anemia have also been reported. As with some other H2-receptor antagonists, there have been extremely rare reports of immune hemolytic anemia.
Dose-related increases in serum transaminase have been reported. In most cases they did not progress with continued therapy and returned to normal at the end of therapy. There have been rare reports of cholestatic or mixed cholestatic-hepatocellular effects. These were usually reversible. Because of the predominance of cholestatic features, severe parenchymal injury is considered highly unlikely. However, as in the occasional liver injury with other H2-receptor antagonists, in exceedingly rare circumstances fatal outcomes have been reported.
There has been reported a single case of biopsy-proven periportal hepatic fibrosis in a patient receiving Tagamet (cimetidine) .
Rare cases of pancreatitis, which cleared on withdrawal of the drug, have been reported.
Small, possibly dose-related increases in plasma creatinine, presumably due to competition for renal tubular secretion, are not uncommon and do not signify deteriorating renal function. Rare cases of interstitial nephritis and urinary retention, which cleared on withdrawal of the drug, have been reported.
There have been rare reports of reversible arthralgia and myalgia; exacerbation of joint symptoms in patients with preexisting arthritis has also been reported. Such symptoms have usually been alleviated by a reduction in Tagamet (cimetidine) dosage. Rare cases of polymyositis have been reported, but no causal relationship has been established.
generalized exfoliative erythroderma have been reported with H2-receptor antagonists. Reversible alopecia has been reported very rarely.
There have been extremely rare reports of strongyloidiasis hyperinfection in immunocompromised patients.
Read the entire FDA prescribing information for Tagamet (Cimetidine)
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