Skip to Content

Acid Controller Maximum Strength Side Effects

Generic Name: famotidine

Note: This page contains information about the side effects of famotidine. Some of the dosage forms included on this document may not apply to the brand name Acid Controller Maximum Strength.

For the Consumer

Applies to famotidine: oral powder for suspension, oral tablet, oral tablet chewable, oral tablet disintegrating

In addition to its needed effects, some unwanted effects may be caused by famotidine (the active ingredient contained in Acid Controller Maximum Strength). In the event that any of these side effects do occur, they may require medical attention.

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when taking famotidine:

  • Bleeding gums
  • blistering, peeling, or loosening of the skin
  • blood in the urine or stools
  • bloody, black, or tarry stools
  • chest pain
  • chills
  • cough or hoarseness
  • diarrhea
  • fever
  • fever with or without chills
  • general feeling of tiredness or weakness
  • high fever
  • itching
  • joint or muscle pain
  • lower back or side pain
  • painful or difficult urination
  • pale skin
  • pinpoint red spots on the skin
  • red, irritated eyes
  • red skin lesions, often with a purple center
  • shortness of breath
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • unusual bleeding or bruising
  • unusual tiredness or weakness
Incidence not known:
  • Abdominal or stomach pain
  • anxiety
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • clay-colored stools
  • dark urine
  • depression
  • difficulty with breathing
  • difficulty with swallowing
  • dizziness
  • dry mouth
  • fainting
  • false sense of well-being
  • fast, irregular, pounding, or racing heartbeat or pulse
  • headache
  • hives
  • hyperventilation
  • irritability
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • loss of appetite
  • loss of bladder control
  • loss of consciousness
  • mood swings
  • nausea
  • nervousness
  • noisy breathing
  • personality changes
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • rash
  • restlessness
  • seizures
  • shaking
  • skin rash
  • swelling around the eyes
  • tightness in the chest
  • total body jerking
  • trouble with sleeping
  • troubled with breathing
  • unpleasant breath odor
  • vision changes
  • vomiting of blood
  • wheezing
  • yellow eyes or skin

Minor Side Effects

Some of the side effects that can occur with famotidine may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

Less common:
  • Difficulty having a bowel movement (stool)
  • Swelling of the breasts or breast soreness in both females and males
Incidence not known:
  • Abdominal or stomach discomfort
  • blemishes on the skin
  • change in taste or bad, unusual or unpleasant (after) taste
  • continuing ringing or buzzing or other unexplained noise in the ears
  • decreased interest in sexual intercourse
  • difficulty with moving
  • dry skin
  • fear
  • hair loss or thinning of the hair
  • hearing loss
  • hives or welts
  • inability to have or keep an erection
  • loss in sexual ability, desire, drive, or performance
  • mood or mental changes
  • muscle cramps
  • muscle stiffness
  • pimples
  • redness of the skin
  • redness of the white part of the eyes
  • seeing, hearing, or feeling things that are not there
  • sleeplessness
  • unable to sleep
  • weight loss

For Healthcare Professionals

Applies to famotidine: compounding powder, intravenous solution, oral powder for reconstitution, oral tablet, oral tablet chewable, oral tablet disintegrating


Gastrointestinal side effects including diarrhea (1.7%) and constipation (1.2%) have been reported. Vomiting, nausea, abdominal discomfort, anorexia, and dry mouth have been reported infrequently. Hypergastrinemia of uncertain clinical significance has also been reported.[Ref]

Nervous system

Confusion, lethargy, delirium, psychosis, agitation, seizures and somnolence have been reported, particularly in elderly patients and patients with multiple medical problems. The frequency of such reactions may be greater than previously believed. The FDA has accumulated 72 reported cases of such central nervous system reactions. All H2-blockers cross the blood-brain barrier and are found in the cerebrospinal fluid.[Ref]

Nervous system side effects have included headache (1% to 4.7%) and dizziness (1.3%). Grand mal seizures, paresthesia, and somnolence have been reported infrequently. Lethargy, confusion, psychosis, and agitation have been reported. Delirium has been reported, which reversed upon drug withdrawal. Convulsions, in patients with impaired renal function, have been reported very rarely.[Ref]


Hepatic side effects have included mild elevations of liver function tests. The clinical significance of these elevations is unknown. Jaundice and cholestatic jaundice have been reported infrequently. Cases of drug-induced hepatitis have also been reported.[Ref]


A 92-year-old male with a history of diabetes mellitus, hypertension, coronary artery disease, and pacemaker implantation for sick sinus syndrome experienced acquired long QT syndrome coincident with famotidine (the active ingredient contained in Acid Controller Maximum Strength) therapy. The patient was admitted with fever, periurethral abscess, and enterococcal sepsis. He was treated with several medications including famotidine. He was administered famotidine at 20 mg per nasogastric tube twice a day after admission. He developed an acute myocardial infarction 10 hours after famotidine therapy. The admission 12-lead electrocardiogram revealed a ventricular paced rhythm at a rate of 60 beats/min and a QTc of 439 ms. After two 20 mg doses of famotidine, the QTc became markedly prolonged at 618 ms. Four days after famotidine was discontinued, the QTc returned close to baseline at 445 ms.[Ref]

Cardiovascular side effects have included decreases in stroke volume and cardiac output and may be clinically significant in patients with preexisting cardiac dysfunction. A variety of arrhythmias, including bradycardia, tachycardia, AV conduction defects (including AV block), and palpitations have also been reported rarely. Prolonged QT interval has been reported very rarely in patients with impaired renal function whose dose/dosing interval of famotidine may not have been adjusted appropriately.[Ref]


Hypersensitivity side effects have infrequently included anaphylaxis, angioedema, orbital or facial edema, urticaria, rash, conjunctival infection, toxic epidermal necrolysis (very rare), erythema multiforme, and Stevens-Johnson syndrome (very rare).[Ref]


Renal side effects have included rare cases of interstitial nephritis.[Ref]


Endocrine side effects have included anti-androgen effects of reversible hyperprolactinemia and gynecomastia.[Ref]


Dermatologic side effects have infrequently included alopecia, acne, pruritus, dry skin, and flushing. At least one case of contact dermatitis in a worker handling famotidine (the active ingredient contained in Acid Controller Maximum Strength) has been reported.[Ref]

A 22-year-old man reported painful, erythematous macules on his chest five days after starting famotidine. These progressed to hemorrhagic, painful erosions of the oral, conjunctival, and urogenital mucosal areas. A lymphocyte transformation test (LTT) was positive indicating an antigenic response to famotidine. The lesions completely resolved in 4 weeks after stopping famotidine and administering prednisolone, tobramycin, oxacillin, cefotaxime, and fluconazole.[Ref]


A case report of agranulocytosis eight days after the initiation of famotidine (the active ingredient contained in Acid Controller Maximum Strength) therapy has been reported in a 87-year-old male. After discontinuation of famotidine, initiation of empiric antibiotic use for the treatment of neutropenic fever, and administration of granulocyte-colony stimulating factor, the patient's white blood cell count and granulocyte count improved.[Ref]

Hematologic side effects including neutropenia have been reported. Rarely, reversible thrombocytopenia, agranulocytosis, pancytopenia, and leukopenia have been reported.[Ref]


Respiratory side effects including bronchospasm and interstitial pneumonia have been reported infrequently.[Ref]


Psychiatric side effects including depression, anxiety, insomnia, hallucinations, and decreased libido have been reported.[Ref]


Musculoskeletal side effects have infrequently included rhabdomyolysis, musculoskeletal pain including muscle cramps and arthralgia.[Ref]


Other side effects including tinnitus, fever, asthenia, fatigue, and taste disorder have been reported infrequently. At least one case of hyperpyrexia in association with famotidine (the active ingredient contained in Acid Controller Maximum Strength) use has been reported.[Ref]


1. Levine JB "Safety profile of H2-receptor antagonists: current status of famotidine." J Int Med Res 17 Suppl 1 (1989): a48-53

2. "Product Information. Pepcid (famotidine)." Merck & Co, Inc, West Point, PA.

3. Rodgers PT, Brengel GR "Famotidine-associated mental status changes." Pharmacotherapy 18 (1998): 404-7

4. Odeh M, Oliven A "Central nervous system reactions associated with famotidine: Report of five cases." J Clin Gastroenterol 27 (1998): 253-4

5. Yuan RY, Kao CR, Sheu JJ, Chen CH, Ho CS "Delirium following a switch from cimetidine to famotidine." Ann Pharmacother 35 (2001): 1045-8

6. Yoshimoto K, Saima S, Echizen H, Nakamura Y, Kondo T, Yagishita Y, Ishizaki T "Famotidine-associated central nervous system reactions and plasma and cerebrospinal drug concentrations in neurosurgical patients with renal failure." Clin Pharmacol Ther 55 (1994): 693-700

7. Cantu TG, Korek JS "Central nervous system reactions to histamine-2 receptor blockers." Ann Intern Med 114 (1991): 1027-34

8. Picotte-Pillmayer D, DiMaggio JR, Baile WF "H-2 blocker delirium." Psychosomatics 36 (1995): 74-7

9. Catalano G, Catalano MC, Alberts VA "Famotidine-associated delirium - a series of six cases." Psychosomatics 37 (1996): 349-55

10. Ament PW, Roth JD, Fox CJ "Famotidine-induced mixed hepatocellular jaundice." Ann Pharmacother 28 (1994): 40-2

11. Hashimoto F, Davis RL, Egli D "Hepatitis following treatments with famotidine and then cimetidine." Ann Pharmacother 28 (1994): 37-9

12. Endo T, Katoh T, Kuichi K, Katsuta Y, Shimizu S, Takano T "Famotidine and acquired long QT syndrome." Am J Med 108 (2000): 438-9

13. Schoenwald PK, Sprung J, Abdelmalak B, Mraovic B, Tetzlaff JE, Gurm HS "Complete atrioventricular block and cardiac arrest following intravenous famotidine administration." Anesthesiology 90 (1999): 623-6

14. Kirch W, Halabi A, Linde M, Santos SR, Ohnhaus EE "Negative effects of famotidine on cardiac performance assessed by noninvasive hemodynamic measurements." Gastroenterology 96 (1989): 1388-92

15. Ahmad S "Famotidine and cardiac arrhythmia." DICP 25 (1991): 315

16. Lucas BD, Williams MA, Mohiuddin SM, LaMadrid LJ, Schroeder LJ, Hilleman DE "Effect of oral H-2-receptor antagonists on left ventricular systolic function and exercise capacity in patients with chronic stable heart failure." Pharmacotherapy 18 (1998): 824-30

17. Lee KW, Kayser SR, Hongo RH, Tseng ZH, Scheinman MM "Famotidine and long QT syndrome." Am J Cardiol 93 (2004): 1325-7

18. Hirayama K, Hanatsuka K, Ikeuchi T, Shida D, Ohtsuka K, Yoshimi F, Hori M, Itabashi M, Koyama A "Famotidine-induced acute interstitial nephritis." Nephrol Dialysis Transplant 13 (1998): 2636-8

19. Galeone F, Giacomelli A, Rossi A, et al "Effect of famotidine on serum immunoreactive parathyroid hormone in chronic hemodialysis patients." Curr Ther Res Clin Exp 44 (1988): 355-8

20. Guven K "Hyperprolactinemia and galactorrhea with standard-dose famotidine therapy." Ann Pharmacother 29 (1995): 788

21. Delpre G, Lapidot M, Lipchitz A, Livni E, Kadish U "Hyperprolactinaemia during famotidine therapy." Lancet 342 (1993): 868

22. Monteseirin J, Conde J "Contact eczema from famotidine." Contact Dermatitis 22 (1990): 290

23. Horiuchi Y, Ikezawa K "Famotidine-induced erythema multiforme: cross-sensitivity with cimetidine." Ann Intern Med 131 (1999): 795

24. Guimaraens D, Gonzales MA, Condesalazar L "Occupational allergic contact dermatitis from intermediate products in famotidine synthesis." Contact Dermatitis 31 (1994): 259-60

25. Brunner M, Vardarman E, Goldermann R, Goerz G, Niederau D, Merk HF, Scharffetterkochanek K "Toxic epidermal necrolysis (lyell syndrome) following famotidine administration." Br J Dermatol 133 (1995): 814-5

26. Oymak O, Akpolat T, Arik N, Yasavul U, Turgan C, Caglar S "Reversible neutropenia and thrombocytopenia during famotidine treatment." Ann Pharmacother 28 (1994): 406-7

27. Zimmermann AE, Katona BG, Hrehorovich VR "Probable famotidine-induced thrombocytopenia." DICP 25 (1991): 678

28. Marcus EL, Clarfield AM, Kleinman Y, Bits H, Darmon D, Da'as N "Agranulocytosis associated with initiation of famotidine therapy." Ann Pharmacother 36 (2002): 267-71

Not all side effects for Acid Controller Maximum Strength may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.