What is Ranitidine?

Histamine H2-receptor antagonists, also known as H2-blockers, are used to treat duodenal ulcers and prevent their return. They are also used to treat gastric ulcers and for some conditions, such as Zollinger-Ellison disease, in which the stomach produces too much acid. In over-the-counter (OTC) strengths, these medicines are used to relieve and/or prevent heartburn, acid indigestion, and sour stomach. H2-blockers may also be used for other conditions as determined by your doctor.

H2-blockers work by decreasing the amount of acid produced by the stomach.

H2-blockers are available both over-the-counter (OTC) and with your doctor's prescription.

For patients taking the nonprescription strengths of these medicines for heartburn, acid indigestion, and sour stomach:

• Do not take the maximum daily dosage continuously for more than 2 weeks, unless directed to do so by your doctor.
• If you have trouble in swallowing, or persistent abdominal pain, see your doctor promptly. These may be signs of a serious condition that may need different treatment.

For patients taking the prescription strengths of these medicines for more serious problems:

• One dose a day—Take it at bedtime, unless otherwise directed.
• Two doses a day—Take one in the morning and one at bedtime.
• Several doses a day—Take them with meals and at bedtime for best results.

It may take several days before this medicine begins to relieve stomach pain. To help relieve this pain, antacids may be taken with the H2-blocker, unless your doctor has told you not to use them. However, you should wait one-half to one hour between taking the antacid and the H2-blocker. Take this medicine for the full time of treatment, even if you begin to feel better. Also, it is important that you keep your appointments with your doctor for check-ups so that your doctor will be better able to tell you when to stop taking this medicine.

For patients taking famotidine chewable tablets:

• Chew the tablets well before swallowing.

For patients taking famotidine oral disintegrating tablets:

• Make sure your hands are dry.
• Leave tablets in unopened package until the time of use, then open the pack and remove the tablet.
• Immediately place the tablet on the tongue.
• The tablet will dissolve in seconds, and you may swallow it with your saliva. You do not need to drink water or other liquid to swallow the tablet.

For patients taking ranitidine effervescent tablets:

• Do not chew, swallow whole or dissolve on the tongue.
• Remove the foil wrapping and dissolve the 150-mg tablet in 6 to 8 ounces of water before drinking.
• For infants and children: Dissolve the 25-mg tablet in no less than 5 mL (1 teaspoonful) of water in a dosing cup. Wait until the tablet is completely dissolved before administering the solution to the infant or child. You may give the medicine to your infant by dropper or oral syringe. Ask your doctor if you are unsure how much medicine to give your infant.

The dose medicines in this class will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For cimetidine:
  • For oral dosage forms (solution and tablets):
    • To treat duodenal or gastric ulcers:
      • Older adults, adults, and teenagers—300 milligrams (mg) four times a day, with meals and at bedtime. Some people may take 400 or 600 mg two times a day, on waking up and at bedtime. Others may take 800 mg at bedtime.
      • Children—20 to 40 mg per kilogram (kg) (9.1 to 18.2 mg per pound) of body weight a day, divided into four doses, taken with meals and at bedtime.
    • To prevent duodenal ulcers:
      • Older adults, adults, and teenagers—300 mg two times a day, on waking up and at bedtime. Instead some people may take 400 mg at bedtime.
      • Children—Dose must be determined by your doctor.
    • To treat heartburn, acid indigestion, and sour stomach:
      • Adults and teenagers—100 to 200 mg with water when symptoms start. The dose may be repeated once in twenty-four hours. Do not take more than 400 mg in twenty-four hours.
      • Children—Dose must be determined by your doctor.
    • To prevent heartburn, acid indigestion, and sour stomach:
      • Adults and teenagers—100 to 200 mg with water up to one hour before eating food or drinking beverages you expect to cause symptoms. Do not take more than 400 mg in twenty-four hours.
      • Children—Dose must be determined by your doctor.
    • To treat conditions in which the stomach produces too much acid:
      • Adults—300 mg four times a day, with meals and at bedtime. Your doctor may change the dose if needed.
      • Children—Dose must be determined by your doctor.
    • To treat gastroesophageal reflux disease:
      • Adults—800 to 1600 mg a day, divided into smaller doses. Treatment usually lasts for 12 weeks.
      • Children—Dose must be determined by your doctor.
  • For injection dosage form:
    • To treat duodenal ulcers, gastric ulcers or conditions in which the stomach produces too much acid:
      • Older adults, adults, and teenagers—300 mg injected into muscle, every six to eight hours. Or, 300 mg injected slowly into a vein every six to eight hours. Instead, 900 mg may be injected slowly into a vein around the clock at the rate of 37.5 mg per hour. Some people may need 150 mg at first, before beginning the around-the-clock treatment.
      • Children—5 to 10 mg per kg (2.3 to 4.5 mg per pound) of body weight injected into a vein or muscle, every six to eight hours.
    • To prevent stress-related bleeding:
      • Older adults, adults, and teenagers—50 mg per hour injected slowly into a vein around the clock for up to 7 days.
      • Children—Dose must be determined by your doctor.

• For famotidine:
  • For oral dosage forms (suspension, tablets, chewable tablets, and oral disintegrating tablets):
    • To treat duodenal ulcers:
      • Older adults, adults, and teenagers—40 milligrams (mg) once a day at bedtime. Some people may take 20 mg two times a day.
      • Children—Dose must be determined by your doctor.
    • To prevent duodenal ulcers:
      • Older adults, adults, and teenagers—20 mg once a day at bedtime.
      • Children—Dose must be determined by your doctor.
    • To treat gastric ulcers:
      • Older adults, adults, and teenagers—40 mg once a day at bedtime.
      • Children—Dose must be determined by your doctor.
    • To treat heartburn, acid indigestion, and sour stomach:
      • Adults and teenagers—10 mg with water when symptoms start. The dose may be repeated once in twenty-four hours. Do not take more than 20 mg in twenty-four hours.
      • Children—Dose must be determined by your doctor.
    • To prevent heartburn, acid indigestion, and sour stomach:
      • Adults and teenagers—10 mg taken one hour before eating a meal you expect to cause symptoms. The dose may be repeated once in twenty-four hours. Do not take more than 20 mg in twenty-four hours.
      • Children—Dose must be determined by your doctor.
    • To treat conditions in which the stomach produces too much acid:
      • Older adults, adults, and children—20 mg every six hours. Your doctor may change the dose if needed.
      • Children—Dose must be determined by your doctor.
    • To treat gastroesophageal reflux disease:
      • Older adults, adults, and teenagers—20 mg two times a day, usually for up to 6 weeks.
      • Children weighing more than 10 kg (22 pounds)—1 to 2 mg per kilogram (kg) (0.5 to 0.9 mg per pound) of body weight a day, divided into two doses.
      • Children weighing less than 10 kg (22 pounds)—1 to 2 mg per kg (0.5 to 0.9 mg per pound) of body weight a day, divided into three doses.
  • For injection dosage form:
    • To treat duodenal ulcers, gastric ulcers, or conditions in which the stomach produces too much acid:
      • Older adults, adults, and teenagers—20 mg injected into a vein, every twelve hours.
      • Children—Dose must be determined by your doctor.

• For nizatidine:
  • For oral dosage forms (capsules and oral solution):
    • To treat duodenal or gastric ulcers:
      • Older adults, adults, and teenagers—300 milligrams (mg) once a day at bedtime. Some people may take 150 mg two times a day.
      • Children—Dose must be determined by your doctor.
    • To prevent duodenal ulcers:
      • Adults and teenagers—150 mg once a day at bedtime.
      • Children—Dose must be determined by your doctor.
    • To prevent heartburn, acid indigestion, and sour stomach:
      • Adults and teenagers—75 mg taken thirty to sixty minutes before eating a meal you expect to cause symptoms. The dose may be repeated once in twenty-four hours.
      • Children—Dose must be determined by your doctor.
    • To treat gastroesophageal reflux disease:
      • Adults and teenagers—150 mg two times a day.
      • Children—Dose must be determined by your doctor.

• For ranitidine:
  • For oral dosage forms (syrup, tablets, effervescent tablets):
    • To treat active duodenal ulcers:
      • Older adults, adults, and teenagers—150 milligrams (mg) two times a day. Some people may take 300 mg once a day at bedtime.
      • Children and infants—2 to 4 mg per kilogram (kg) (1 to 2 mg per pound) of body weight twice a day. However, the total dose will not be more than 300 mg a day.
    • To maintain healing of duodenal ulcers:
      • Older adults, adults, and teenagers—150 mg once a day at bedtime.
      • Children and infants—2 to 4 mg per kg (1 to 2 mg per pound) of body weight once a day. However, the total dose will not be more than 150 mg a day.
    • To treat erosive esophagitis:
      • Older adults, adults, and teenagers—150 mg four times a day
      • Children and infants—5 to 10 mg per kg (2.3 to 4.6 mg per pound) of body weight per day, usually divided and given in two doses during the day.
    • To maintain healing of erosive esophagitis:
      • Older adults, adults, and teenagers—150 mg twice a day
      • Children and infants—Dose must be determined by your doctor.
    • To treat benign gastric ulcers:
      • Older adults, adults, and teenagers—150 mg two times a day.
      • Children and infants—2 to 4 mg per kg (1 to 2 mg per pound) of body weight twice a day. However, the total dose will not be more than 300 mg a day.
    • To maintain healing of gastric ulcers:
      • Older adults, adults, and teenagers—150 mg once a day at bedtime.
      • Children and infants—2 to 4 mg per kg (1 to 2 mg per pound) of body weight once a day. However, the total dose will not be more than 150 mg a day.
    • To treat heartburn, acid indigestion, and sour stomach:
      • Adults and teenagers—150 mg with water when symptoms start. The dose may be repeated once in twenty-four hours. Do not take more than 300 mg in twenty-four hours.
      • Children—Dose must be determined by your doctor.
    • To prevent heartburn, acid indigestion, and sour stomach:
      • Adults and teenagers—150 mg with water taken thirty to sixty minutes before eating a meal or drinking beverages you expect to cause symptoms. Do not take more than 300 mg in twenty-four hours.
      • Children—Dose must be determined by your doctor.
    • To treat some conditions in which the stomach produces too much acid:
      • Older adults, adults, and teenagers—150 mg two times a day. Your doctor may change the dose if needed.
      • Children—Dose must be determined by your doctor.
    • To treat gastroesophageal reflux disease:
      • Older adults, adults, and teenagers—150 mg two times a day. Your dose may be increased if needed.
      • Children and infants—5 to 10 mg per kg (2.3 to 4.6 mg per pound) of body weight per day, usually divided and given in two doses during the day.
  • For injection dosage form:
    • To treat duodenal ulcers, gastric ulcers, or conditions in which the stomach produces too much acid:
      • Older adults, adults, and teenagers—50 milligrams (mg) injected into a muscle every six to eight hours. Or, 50 mg injected slowly into a vein every six to eight hours. Instead, you may receive 6.25 mg per hour injected slowly into a vein around the clock. However, most people will usually not need more than 400 mg a day.
    • To treat duodenal or gastric ulcers:
      • Children—2 to 4 mg per kilogram (kg) (1 to 2 mg per pound) of body weight per day, usually divided and injected slowly into a vein every six to eight hours. However the total dose will not be more than 50 mg every six to eight hours.

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Tell your doctor if you have ever had any unusual or allergic reaction to medicines in this group or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

This medicine has been tested in children and, in effective doses, has not been shown to cause different side effects or problems than it does in adults when used for short periods of time.

Confusion and dizziness may be especially likely to occur in elderly patients, who are usually more sensitive than younger adults to the effects of H2-blockers.

H2-blockers have not been studied in pregnant women. In animal studies, famotidine and ranitidine have not been shown to cause birth defects or other problems. However, one study in rats suggested that cimetidine may affect male sexual development. More studies are needed to confirm this. Also, studies in rabbits with very high doses have shown that nizatidine causes miscarriages and low birth weights. Make sure your doctor knows if you are pregnant or if you may become pregnant before taking H2-blockers.

Cimetidine, famotidine, nizatidine, and ranitidine pass into the breast milk and may cause unwanted effects, such as decreased amounts of stomach acid and increased excitement, in the nursing baby. It may be necessary for you to take another medicine or to stop breast-feeding during treatment. Be sure you have discussed the risks and benefits of the medicine with your doctor.

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking any of these medicines, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using medicines in this class with any of the following medicines is not recommended. Your doctor may decide not to treat you with a medication in this class or change some of the other medicines you take.

• Amifampridine
• Amisulpride
• Bepridil
• Cisapride
• Dofetilide
• Dronedarone
• Mesoridazine
• Pimozide
• Piperaquine
• Saquinavir
• Sparfloxacin
• Terfenadine
• Thioridazine
• Ziprasidone

Using medicines in this class with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Acalabrutinib
• Alfentanil
• Alosetron
• Amiodarone
• Amprenavir
• Anagrelide
• Aripiprazole
• Aripiprazole Lauroxil
• Arsenic Trioxide
• Atazanavir
• Benzhydrocodone
• Buprenorphine
• Bupropion
• Buserelin
• Capecitabine
• Carmustine
• Chloroquine
• Citalopram
• Clarithromycin
• Clopidogrel
• Clozapine
• Codeine
• Crizotinib
• Dabrafenib
• Dasatinib
• Degarelix
• Delamanid
• Delavirdine
• Deslorelin
• Deutetrabenazine
• Dihydrocodeine
• Domperidone
• Donepezil
• Doxifluridine
• Efavirenz
• Eliglustat
• Encorafenib
• Erlotinib
• Escitalopram
• Fentanyl
• Fingolimod
• Fluconazole
• Fluorouracil
• Fluoxetine
• Fosamprenavir
• Foscarnet
• Gefitinib
• Gonadorelin
• Goserelin
• Histrelin
• Hydrocodone
• Hydroxychloroquine
• Hydroxyzine
• Inotuzumab Ozogamicin
• Ivabradine
• Ivosidenib
• Ketoconazole
• Ledipasvir
• Leuprolide
• Levofloxacin
• Lofexidine
• Macimorelin
• Meperidine
• Methadone
• Metronidazole
• Morphine
• Morphine Sulfate Liposome
• Moxifloxacin
• Nafarelin
• Neratinib
• Ondansetron
• Osimertinib
• Oxycodone
• Oxymorphone
• Panobinostat
• Pasireotide
• Pazopanib
• Pentazocine
• Pimavanserin
• Piperaquine
• Pitolisant
• Posaconazole
• Quetiapine
• Ribociclib
• Rilpivirine
• Secretin Human
• Sertraline
• Sevoflurane
• Sotalol
• Sufentanil
• Sulpiride
• Tacrolimus
• Tegafur
• Theophylline
• Tizanidine
• Tolazoline
• Tramadol
• Triptorelin
• Vandetanib
• Vemurafenib
• Vinflunine
• Vismodegib
• Zalcitabine
• Zuclopenthixol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

The presence of other medical problems may affect the use of medicines in this class. Make sure you tell your doctor if you have any other medical problems, especially:

• Kidney disease or
• Liver disease—The H2-blocker may build up in the bloodstream, which may increase the risk of side effects.

• Phenylketonuria (PKU)—Some H2-blockers contain aspartame. Aspartame is converted to phenylalanine in the body and must be used with caution in patients with PKU. The Pepcid AC brand of famotidine chewable tablets contains 1.4 mg of phenylalanine per 10-mg dose. The Pepcid RPD brand of famotidine oral dispersible tablets contains 1.05 mg of phenylalanine per 20-mg dose. The Zantac brand of ranitidine EFFERdose tablets contains 2.81 mg of phenylalanine per 25-mg dose and 16.84 mg of phenylalanine per 150-mg dose.

• Porphyria (rare family disease that affects the way your body digests food)—May make condition worse in patients who have acute porphyria

• Weakened immune system (difficulty fighting infection)—Decrease in stomach acid caused by H2-blockers may increase the possibility of a certain type of infection

Some tests may be affected by this medicine. Tell the doctor in charge that you are taking this medicine before:

• You have any skin tests for allergies.
• You have any tests to determine how much acid your stomach produces.

Remember that certain medicines, such as aspirin, and certain foods and drinks (e.g., citrus products, carbonated drinks) irritate the stomach and may make your problem worse.

Cigarette smoking tends to decrease the effect of H2-blockers by increasing the amount of acid produced by the stomach. This is more likely to affect the stomach's nighttime production of acid. While taking H2-blockers, stop smoking completely, or at least do not smoke after taking the last dose of the day.

Drinking alcoholic beverages while taking an H2-receptor antagonist has been reported to increase the blood levels of alcohol. You should consult your health care professional for guidance.

Check with your doctor if your ulcer pain continues or gets worse.