Generic name: Cimetidine.

Tagamet is an anti-ulcer/gastric acid secretion inhibitor. It blocks the effects of histamine in the stomach, which reduces stomach acid secretion.

Quick Facts About Tagamet


Used to treat stomach and intestinal ulcers and related conditions, including: active duodenal (upper intestinal) ulcers: active benign stomach ulcers; erosive gastroesophageal reflux disease (backflow of stomach acid contents); prevention of upper abdominal bleeding in the critically ill; and excess acid conditions such as Zollinger-Ellison syndrome (peptic ulcer with too much acid). Also used for maintenance therapy for duodenal ulcer; to treat acne; stress-induced ulcers; herpes virus infections (including shingles); abnormal hair growth in women; and overactivity of parathyroid gland.

Tagamet Dosage

Take with or without food. May take several days to feel effects of Tagamet; continue taking medication even if there seems to be no reduction of symptoms. Avoid excessive amounts of caffeine; do not take antacids within 1 to 2 hours of taking Tagamet

  • Usual adult dose: for active duodenal ulcer — 800 milligrams taken once per day at bedtime; or 300 milligrams taken 4 times per day with meals and at bedtime; 400 milligrams taken twice per day in the morning and bedtime. Most therapy lasts 4 weeks. For active benign gastric ulcer — 800 milligrams taken once per day at bedtime or 300 milligrams taken 4 times per day with meals and at bedtime. For erosive gastroesophageal reflux disease — total of 1,600 milligrams per day divided into 2 doses of 800 milligrams or 400 milligrams taken 4 times per day for 12 weeks. For pathological hypersecretory condition — 300 milligrams taken 4 times per day with meals and at bedtime. Doctor may prescribe up to 2,400 milligrams per day. Seniors — may be prescribed lower dose depending on individual needs.
  • Usual child dose: not generally prescribed for children under 16 years. However, doctor may use in limited cases. Doses range from 20 to 40 milligrams per 2.2 pounds of body weight.
  • Missed dose: take as soon as possible, unless almost time for next dose. In that case, do not take missed dose; go back to regular schedule. Do not double doses.

Tagamet Side Effects

Overdose symptoms:

respiratory failure, increased heartbeat, exaggerated side effects, or unresponsiveness. If you suspect an overdose, immediately seek medical attention.

More common side effects: breast development in men, headache.

Less common Tagamet side effects: agitation, anxiety, confusion, depression, disorientation, hallucinations may occur in the severely ill being treated for over 1 month — these are temporary. Rare side effects: allergic reactions, anemia, blood disorders, diarrhea, dizziness, fever, hair loss, impotence, inability to urinate, joint pain, kidney disorders, liver disorders, mild rash, muscle pain, pancreas inflammation, rapid heartbeat, skin inflammation or peeling, sleepiness, slow heartbeat.


Inform your doctor before combining Tagamet with:

anti-arrhythmic heart medications such as Cordarone, Tonocard, Quinidex, and Procan; antidiabetic medications such as Micronase and Glucotrol; antifungal medications such as Diflucan and Nizoral; aspirin; Augmentin; benzodiazepine tranquilizers such as Valium and Librium; beta-blockers such as Inderal and Lopressor; calcium blockers such as Cardizem, Calan, and Procardia; chlorpromazine (Thorazine); cisapride (Propulsid); cyclosporine (Sandimmune); digoxin (Lanoxin); narcotic pain relievers such as Demerol and Morphine; metoclopramide (Reglan); metronidazole (Flagyl); nicotine (Nicoderm); paroxetine (Paxil); pentoxifylline (Trental); phenytoin (Dilantin); quinine (Quinamm); sucralfate (Carafate); theophylline (Theo-Dur); warfarin (Coumadin).

Avoid alcohol during Tagamet therapy; intensifies the effects of alcohol. Smoking cigarettes during Tagamet therapy may slow healing process.

Special Cautions

If pregnant or planning to become pregnant, inform your doctor immediately. Appears in breast milk; could affect a nursing infant.

Seniors are generally prescribed lower doses.

In limited cases is prescribed for children under 16 years.

  • Do not take if allergic to Tagamet
  • Ulcers can be completely healed with short-term treatment of Tagamet. Recurrence rate may be slightly higher with Tagamet than other forms of therapy; however, Tagamet is usually prescribed for the severe cases.
  • Tell your doctor if you are being treated for a kidney or liver disorder.
  • Individuals over age 50, or with kidney disease, or those who are critically ill, may experience mental confusion during Tagamet therapy. This is a temporary condition.


HealthSurvey.org provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Tagamet side effects, please contact your healthcare provider