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Thioridazine

Drug Information

Thioridazine is used to treat symptoms associated with psychosis; depression with worry and restlessness in adults; irritability, worry, and fear in elderly; and severe behavioral problems in children, including fighting and hyperactivity. It is classified as a phenothiazine neuroleptic.

Common brand names:

Mellaril

Summary of Interactions with Vitamins, Herbs, & Foods

What Are Nutrient Interactions
Types of interactions: Beneficial Adverse Check

Replenish Depleted Nutrients

  • Vitamin A

    A review of people taking thioridazine showed that they had higher blood levels of vitamin A than did individuals not using the drug.1 More research is necessary to determine whether taking vitamin A supplements with thioridazine might cause dangerously high vitamin A levels. Until more is known, people taking thioridazine should exercise caution with vitamin A supplementation and be alert for side effects such as bone pain, headaches, dry scaly skin, and hair loss.

Reduce Side Effects

  • Coenzyme Q10

    Phenothiazine drugs like thioridazine can cause changes in heart activity in some people, which might be prevented with coenzyme Q10 supplementation.2 Therefore, some doctors and pharmacists may recommend coenzyme Q10 supplements to individuals taking thioridazine.

  • Potassium

    Some people taking thioridazine experience changes in the electrical activity of the heart, which sometimes improve with potassium supplementation.3 More research is needed to determine if people taking thioridazine might prevent heart problems by supplementing with potassium.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Support Medicine

  • Vitamin B3

    In a controlled study, individuals taking thioridazine for psychosis cooperated better and withdrew less from other people when niacin (nicotinic acid), 300–1,500 mg each day, was added.4 Whether people who are taking thioridazine for other mental health problems might benefit from niacin supplementation is unknown.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Reduces Effectiveness

  • none

Potential Negative Interaction

  • Bacopa

    An animal study found that the effects of chlorpromazine, a drug similar to (perphenazine, prochlorperazine, thioridazine), were enhanced when a bacopa extract was given along with it.5 Until more is known, people taking medications from this family of drugs (called phenothiazines) should not take bacopa.

Explanation Required 

  • Vitamin C

    Taking phenothiazine drugs can stop menstruation in some women. A 45-year-old woman taking thioridazine started menstruating once she began supplementing with 6 grams of vitamin C daily.6 Controlled studies are needed to determine whether women taking thioridazine, who are experiencing menstrual changes, might benefit from supplemental vitamin C. Vitamin C might also enhance the effectiveness of neuroleptic drugs, such as thioridazine, in the treatment of schizophrenia. One uncontrolled study showed that 10 of 13 individuals experienced a reduction in disorganized thoughts, hallucinations, and suspicious thoughts when 8 grams of vitamin C was added to their daily drug therapy.7 Controlled studies are needed to determine whether people taking thioridazine for schizophrenia might benefit from vitamin C supplementation.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.

References

1. Curtis JL. Effects of medication on plasma vitamin A concentrations. Clin Chem 1976;22:695.

2. Kishi T, Makino K, Okamoto T, et al. In Yamamura Y, Folkers K, Ito Y, eds. Biochemical and Clinical Aspects of Coenzyme Q, Volume 2. Amsterdam: Elsevier/North Holland Biomedical Press, 1980, 139–57.

3. Sydney MA. Ventricular arrhythmias associated with use of thioridazine hydrochloride in alcohol withdrawal. Br Med J 1973;4:467.

4. Lehmann HE, Ban TA, Saxena BM. Nicotinic acid, thioridazine, fluoxymesterone and their combinations in hospitalized geriatric patients. Can Psychiatr Assoc J 1972;17:315–20.

5. Ganguly DK, Malhotra CL. Some behavioral effects of an active fraction from Herpestis monniera Linn. (Brahmi). Indian J Med Res 1967;55:473–82.

6. Kanofsky JD, Kay SR, Lindenmayer JP, Seifter E. Ascorbic acid action in neuroleptic-associated amenorrhea. J Clin Psychopharmacol 1989;9:388–9 [letter].

7. Beauclair L, Vinogradov S, Riney SJ, et al. An adjunctive role for ascorbic acid in the treatment of schizophrenia? J Clin Psychopharmacol 1987;7:282–3.

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