Pepcid (famotidine) and Zantac (ranitidine) are both in the same family of drugs and are extremely similar. There are no large scale studies comparing their effectiveness against one another unfortunately. These drugs appear to be essentially identical in terms of effectiveness, adverse reactions and tolerability. In the few small studies that did compare them, they both showed similar healing rates for ulcers and a similar reduction in the symptoms of acid reflux.
Overall, most studies that were conducted conclude that there is no statistically significant difference in terms of effectives between Pepcid (famotidine) and Zantac (ranitidine).
Pepcid (famotidine) is a H2 blocker (histamine 2 receptor blocker) that is used to decrease acid secretion in the stomach in order to treat acid reflux, also known as heart burn, and to treat gastric ulcers. Famotidine is typically taken twice a day and does not have many side effects associated with it. Pepcid comes in dosages of 20 mg and 40 mg.
Zantac (ranitidine) is also a H2 blocker that is used to decrease acid secretion in the stomach. It is also used to treat ulcers and heart burn and is dosed twice daily. Zantac comes in dosages of 75 mg and 150 mg.
It is important to note that even though there is a significant difference in mg dose between the two drugs, that does not correlate to difference in potency. Different drug compounds require different dosages to have the required effect.
In terms of side effects, famotidine and ranitidine again are very similar. The side effects associated with them including dizziness, agitation, and constipation; however, these side effects are relatively uncommon and both drugs are very safe.
Both famotidine and ranitidine have the same mechanism of action and are dosed twice daily when used to treat heartburn over-the-counter. Famotidine works within 1-3 hours while ranitidine works within 2-3 hours. Both drugs will require a dosage adjustment if you have any issues with your kidneys (for example, if you have renal disease or receive dialysis).
Response to both drugs will vary by individual and it may take some trial and error to determine which works best for your symptoms.