Also indexed as: Apo-Thioridazine®, Mellaril®,
Melleril®, Rideril®
Thioridazine is used to treat symptoms associated with psychosis; depression with worry and restlessness in adults;
irritability, worry, and fear in elderly; and severe behavioural problems in children,
including fighting and hyperactivity. It is
classified as a phenothiazine neuroleptic.
Summary of
Interactions with Vitamins, Herbs, and Foods
In some cases, a 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 A
|
| May be Beneficial: Side effect
reduction/prevention—Taking these supplements may help reduce the likelihood and/or
severity of a potential side effect caused by the medication. |
Coenzyme Q10
Potassium*
|
| May be Beneficial: Supportive
interaction—Taking these supplements may support or otherwise help your medication
work better. |
Niacin*
|
Avoid: Adverse interaction—Avoid these supplements when taking this
medication because taking them together may cause undesirable or dangerous results. |
Bacopa
Lithium*
|
Check: Other—Before taking any of these supplements or eating any of
these foods with your medication, read this article in full for details. |
Vitamin C*
|
| Reduced drug
absorption/bioavailability |
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
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.
Potassium
Some people taking thioridazine experience changes in the electrical activity of the heart,
which sometimes improve with potassium supplementation.2 More research is needed to
determine if people taking thioridazine might prevent heart problems by supplementing with
potassium.
Niacin (nicotinic
acid)
In a controlled study, individuals taking thioridazine for psychosis cooperated better and
withdrew less from other people when niacin, 300–1,500 mg each day, was
added.3 Whether people who are taking thioridazine for other mental health problems
might benefit from niacin supplementation is unknown.
Coenzyme
Q10
Phenothiazine drugs like thioridazine can cause changes in heart activity in some people,
which might be prevented with coenzyme Q10 supplementation.4 Therefore, some
doctors and pharmacists may recommend coenzyme Q10 supplements to individuals taking
thioridazine.
Lithium
Lithium is a mineral that may be present in some supplements and is also used in large amounts
to treat mood disorders such as bipolar
disorder (manic depression). One study reviewed four cases in which individuals stabilised
on lithium medication developed side effects such as delirium, seizures, and abnormal
electrical activity in the brain when thioridazine was added.5 Further research is
needed to determine whether similar side effects might occur in individuals taking
thioridazine and supplemental lithium.
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.
Interactions with Herbs
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.8 Until more is known, people taking medications from this family of drugs
(called phenothiazines) should not take bacopa.
Interactions with Foods and Other Compounds
Alcohol
Drinking alcoholic beverages while taking thioridazine may enhance the actions of alcohol,
such as drowsiness, dizziness, and lack of concentration,9 and should be avoided.
Two individuals withdrawing from chronic alcohol consumption experienced serious changes in
heart function when they were given thioridazine;10 therefore, the drug should be
used with caution in people who are attempting to quit drinking.
References
(To view, roll mouse over heading; to hide, click on heading)
1. Curtis JL. Effects of medication on plasma vitamin A concentrations.
Clin Chem 1976;22:695.
2. Sydney MA. Ventricular arrhythmias associated with use of thioridazine
hydrochloride in alcohol withdrawal. Br Med J 1973;4:467.
3. 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.
4. 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.
5. Spring GK. Neurotoxicity with combined use of lithium and
thioridazine. J Clin Psychiatry 1979;40:135–8.
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.
8. Ganguly DK, Malhotra CL. Some behavioral effects of an active fraction
from Herpestis monniera Linn. (Brahmi). Indian J Med Res 1967;55:473–82.
9. Sifton DW, ed. Physicians Desk Reference. Montvale, NJ:
Medical Economics Company, Inc., 2000, 1973–4.
10. Sydney MA. Ventricular arrhythmias associated with use of
thioridazine hydrochloride in alcohol withdrawal. Br Med J 1973;4:467.
Copyright © 2006 Healthnotes, Inc. All rights reserved.
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Learn more about the authors of Using Medicines
with Vitamins and Herbs
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 chemist for any health problem and before using any supplements or before
making any changes in prescribed medications. Information expires March 2007.
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