Methyldopa
Methyldopa is a drug used to lower blood pressure in people with hypertension (high blood pressure).
Summary of Interactions with Vitamins, Herbs, and Foods
In some cases, an herb or supplement may appear in more than one category, which may seem contradictory. For clarification, read the full article for details about the summarized interactions.
 May Be Beneficial: Depletion or interference—The medication may deplete or interfere with the absorption or function of the nutrient. Taking these nutrients may help replenish them. | Vitamin B12* |
 Avoid: Reduced drug absorption/bioavailability—Avoid these supplements when taking this medication since the supplement may decrease the absorption and/or activity of the medication in the body. | Iron |
| Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results. | Sodium |
| Side effect reduction/prevention | None known |
| Supportive interaction | None known |
An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.
Interactions with Dietary Supplements
Iron
Iron supplements have been found to decrease methyldopa absorption.1 2 Taking methyldopa two hours before or after iron-containing products can help avoid this interaction.
Vitamin B12
Methyldopa can decrease vitamin B12 levels, thus increasing the risk of vitamin B12 deficiency.3
Sodium
Excess dietary sodium (salt) intake can cause fluid retention and interfere with the blood pressure lowering action of methyldopa.4 Reducing the use of table salt and heavily salted foods during methyldopa therapy reduces the likelihood of this interference.
Interactions with Foods and Other Compounds
Food
Food can interfere with methyldopa absorption.5 Taking methyldopa one hour before or two hours after eating can prevent this interference.
References (To view, roll mouse over the "References" heading; to hide, click on the heading)
1. Campbell NR, Hasinoff BB. Iron supplements: A common cause of drug interactions. Brit J Clin Pharmacol 1991;31:251–5.
2. Campbell N, Paddock V, Sundaram R. Alteration of methyldopa absorption, metabolism, and blood pressure control caused by ferrous sulfate and gluconate. Clin Pharmacol Ther 1988;43:381–6.
3. Holt GA. Food & Drug Interactions. Chicago: Precept Press, 1998, 74.
4. Holt GA. Food & Drug Interactions. Chicago: Precept Press, 1998, 171–2 .
5. Holt GA. Food & Drug Interactions. Chicago: Precept Press, 1998, 170–1.
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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2009.