Drug Interactions:
H2 Blockers
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Vitamin B12 - Probable Need for Supplementation
Folate - Supplementation Possibly Helpful
Minerals - Supplementation Possibly Helpful
Magnesium - Take at a Different Time of Day
Vitamin D - Possible Inhibition by Cimetidine
Medications in this family sharply decrease stomach acid production. They are widely used for the treatment of ulcers as well as for mild cases of esophageal reflux (heartburn).
Drugs that fall into this family include
- cimetidine (Tagamet, Tagamet HB)
- famotidine (Pepcid, Pepcid AC, Pepcid RPD)
- nizatidine (Axid, Axid AR)
- ranitidine hydrochloride (Zantac, Zantac EFFERdose, Zantac GELdose, Zantac 75)
- and others
Vitamin B12
Probable Need for Supplementation
H2-receptor blockers appear to impair the absorption of vitamin B12 from food.1,2,3 This is thought to occur because the vitamin B12 in food is attached to proteins. Stomach acid separates them and allows the B12 to be absorbed.
The solution? If you regularly use H2 blockers, take B12 supplements. They can be absorbed easily because they are not attached to proteins.
Folate
Supplementation Possibly Helpful
There is some evidence that H2 blockers may slightly reduce the absorption of folate.4 Folate is an important nutrient and one that is commonly deficient in the diet; so if you are taking H2 blockers, you should probably take folate supplements, too.
Minerals
Supplementation Possibly Helpful
By reducing stomach acid levels, H2 blockers might interfere with the absorption of iron, zinc, and perhaps other minerals.5–8 Taking mineral supplements that provide the U.S. Dietary Reference Intake (formerly known as the Recommended Dietary Allowance) of these substances should help.
Magnesium
Take at a Different Time of Day
Magnesium supplements may interfere with the absorption of H2 blockers.9 However, the interference may be too minor to cause a real problem. If you think your magnesium supplements are interfering with your medication, you can get around the problem by taking these minerals at least 2 hours before or after you take an H2-blocking medication.
Vitamin D
Possible Inhibition by Cimetidine
Cimetidine may interfere with vitamin D metabolism.10,11,12 Other H2 blockers may not interact. Whether taking more vitamin D is useful remains unknown.
View References
Last reviewed March 2002 by Medical Review Board
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