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: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.