Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started
My Medicine

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Cafatine PB rectal



This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

When these two medicines are taken together, your body may process the medicines differently.

What might happen:

The effects of your barbiturate may increase and cause increased drowsiness, slowed breathing, and a decrease in blood pressure. The effects of your phenothiazine may decrease and it may not work as well.

What you should do about this interaction:

If you experience excessive drowsiness, slowed breathing, weakness, fatigue, or dizziness, contact your doctor. It may be necessary to monitor your blood pressure and breathing rate. Let your doctor know if your symptoms worsen. Your doctor may need to adjust the dose of your medicines.Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.


1.Phenergan (promethazine hydrochloride) US prescribing information. Baxter Healthcare Corporation December, 2006.

2.Chlorpromazine hydrochloride US prescribing information. Baxter Healthcare Corporation October, 2006.

3.Hatanaka T, Negishi S, Katayama K, Kakemi M, Koizumi T. The pharmacodynamic and pharmacokinetic interaction of pentobarbital and chlorpromazine in rats. J Pharmacobiodyn 1988 Jan;11(1):47-52.

4.Hatanaka T, Sato S, Endoh M, Katayama K, Kakemi M, Koizumi T. Effect of chlorpromazine on the pharmacokinetics and pharmacodynamics of pentobarbital in rats. J Pharmacobiodyn 1988 Jan;11(1):18-30.

5.Forrest FM, Forrest IS, Serra MT. Modification of chlorpromazine metabolism by some other drugs frequently administered to psychiatric patients. Biol Psychiatry 1970 Jan;2(1):53-8.

6.Curry SH, Marshall JH, Davis JM, Janowsky DS. Chlorpromazine plasma levels and effects. Arch Gen Psychiatry 1970 Apr;22(4):289-96.

7.Loga S, Curry S, Lader M. Interactions of orphenadrine and phenobarbitone with chlorpromazine: plasma concentrations and effects in man. Br J Clin Pharmacol 1975 Jun;2(3):197-208.

8.Gay PE, Madsen JA. Interaction between phenobarbital and thioridazine. Neurology 1983 Dec;33(12):1631-2.

9.Ellenor GL, Musa MN, Beuthin FC. Phenobarbital--thioridazine interaction in man. Res Commun Chem Pathol Pharmacol 1978 Jul;21(1):185-8.

10.Linnoila M, Viukari M, Vaisanen K, Auvinen J. Effect of anticonvulsants on plasma haloperidol and thioridazine levels. Am J Psychiatry 1980 Jul; 137(7):819-21.

Selected from data included with permission and copyrighted by First Databank, Inc. This copyrighted material has been downloaded from a licensed data provider and is not for distribution, expect as may be authorized by the applicable terms of use.

CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.

More about Drugs and Medications


Subscribe to free WebMD newsletters.

  • WebMD Daily

    WebMD Daily

    Subscribe to the WebMD Daily, and you'll get today's top health news and trending topics, and the latest and best information from WebMD.

  • Men's Health

    Men's Health

    Subscribe to the Men's Health newsletter for the latest on disease prevention, fitness, sex, nutrition, and more from WebMD.

  • Women's Health

    Women's Health

    Subscribe to the Women's Health newsletter for the latest on disease prevention, fitness, sex, diet, anti-aging, and more from WebMD.

By clicking Submit, I agree to the WebMD Terms & Conditions & Privacy Policy and understand that I may opt out of WebMD subscriptions at any time.

URAC: Accredited Health Web Site TRUSTe online privacy certification HONcode Seal AdChoices