Haloperidol

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Also indexed as:

Haldol

Haloperidol is a drug used to treat people with psychotic disorders, including schizophrenia.

Herbs

Summary of Interactions for Haloperidol

Depletion or interference	Iron* Sodium*
Adverse interaction	None known
Side effect reduction/prevention	Ginkgo biloba Milk thistle* Vitamin E
Supportive interaction	Glycine
Reduced drug absorption/bioavailability	Coffee and tea*
Other (see text)	Potassium

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 Supplements

Glycine

Two double-blind studies have found that 0.4-0.8 mg/kg body weight per day of glycine can reduce the so-called negative symptoms of schizophrenia when combined with haloperidol and related drugs.^{1, 2} Negative symptoms include reduced emotional expression or general activity. The action of glycine in combination with the drugs was greater than the drugs alone, suggesting a synergistic action. Another double-blind study using approximately half the amount in the positive studies could not find any benefit from adding glycine to antipsychotic drug therapy.³ Patients with low blood levels of glycine appeared to improve the most when given glycine in addition to their antipsychotic drugs.⁴ No side effects were noticed in these studies, even when more than 30 grams of glycine were given daily.

Iron

Haloperidol may cause decreased blood levels of iron.⁵ The importance of this interaction remains unclear. Iron should not be supplemented unless a deficiency is diagnosed.

Potassium

Haloperidol may cause hyperkalemia (high blood levels of potassium) or hypokalemia (low blood levels of potassium).⁶ The incidence and severity of these changes remains unclear. Serum potassium can be measured by any doctor.

Vitamin E

Haloperidol and related antipsychotic drugs can cause a movement disorder called tardive dyskinesia. Several double-blind studies suggest that vitamin E may be beneficial for treatment of tardive dyskinesia.⁷ Taking the large amount of 1,600 IU per day of vitamin E simultaneously with antipsychotic drugs has also been shown to lessen symptoms of tardive dyskinesia.⁸ It is unknown if combining vitamin E with haloperidol could prevent tardive dyskinesia.

Sodium

Haloperidol may cause hyponatremia (low blood levels of sodium).⁹ The incidence and severity of these changes remains unclear.

Interactions with Herbs

Milk thistle(Silybum marianum)

Haloperidol may cause liver damage. A double-blind study in 60 women treated with drugs such as haloperidol were given 800 mg per day silymarin extract made from milk thistle.¹⁰ Test subjects who were given silymarin experienced a significant decrease in free radical levels, unlike those given placebo.

Ginkgo biloba

In a double-blind trial, supplementation of schizophrenic patients with Ginkgo biloba extract, in the amount of 250 mg per 2.2 pounds of body weight per day for 12 weeks, enhanced the effectiveness of haloperidol and also reduced the side effects of the drug.¹¹

Other Interactions

Coffee and Tea

Coffee and tea are reported to cause precipitation of haloperidol in the test tube.¹² If this interaction happens in people, it would reduce the amount of haloperidol absorbed and the effectiveness of therapy. People taking haloperidol may avoid this possible interaction by taking haloperidol one hour before or two hours after drinking coffee or tea.

Alcohol

Haloperidol may cause drowsiness.¹³ Alcohol may compound this drowsiness and increase the risk of accidents during activities requiring alertness. People should avoid alcohol-containing products during haloperidol therapy.

References

1. Heresco-Levy U, Javitt DC, Ermilov M, et al. Double-blind, placebo-controlled, crossover trial of glycine adjuvant therapy for treatment-resistant schizophrenia. Br J Psychiatry 1996;169:610-7.
2. Javitt DC, Zylberman I, Zukin SR, et al. Amelioration of negative symptoms in schizophrenia by glycine. Am J Psychiatry 1994;151:1234-6.
3. Potkin SG, Costa J, Roy S, et al. Glycine in treatment of schizophrenia-theory and preliminary results. In: Meltzer HY (ed). Novel Antipsychotic Drugs. New York: Raven Press, 1990:179-88.
4. Heresco-Levy U, Javitt DC, Ermilov M, et al. Double-blind, placebo-controlled, crossover trial of glycine adjuvant therapy for treatment-resistant schizophrenia. Br J Psychiatry 1996;169:610-7.
5. Threlkeld DS, ed. Central Nervous System Drugs, Antipsychotic Agents. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, May 1998, 266k-6m.
6. Threlkeld DS, ed. Central Nervous System Drugs, Antipsychotic Agents. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, May 1998, 266k-6m.
7. Adler LA, Peselow E, Rotrosen J, et al. Vitamin E treatment of tardive dyskinesia. Am J Psychiatry 1993;150:1405-7.
8. Adler LA, Edson R, Lavori P, et al. Long-term treatment effects of vitamin E for tardive dyskinesia. Biol Psychiatry 1998;43:868-72.
9. Threlkeld DS, ed. Central Nervous System Drugs, Antipsychotic Agents. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, May 1998, 266k-6m.
10. Palasciano G, Portincasa P, Palmieri V, et al. The effect of silymarin on plasma levels of malon-dialdehyde in patients receiving long-term treatment with psychotropic drugs. Curr Ther Res 1994;55:537-45.
11. Zhang XY, Zhou DF, Zhang PY, et al. A double-blind, placebo-controlled trial of extract of Ginkgo biloba added to haloperidol in treatment-resistant patients with schizophrenia. J Clin Psychiatry 2001;62:878-83.
12. Lasswell WL Jr, Weber SS, Wilkins JM. In vitro interaction of neuroleptics and tricyclic antidepressants with coffee, tea, and gallotannic acid. J Pharm Sci 1984;73:1056-8.
13. Threlkeld DS, ed. Central Nervous System Drugs, Antipsychotic Agents. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, May 1998, 266k-6m.

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Last Review: 09-01-2007

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