Skip to content
My WebMD Sign In, Sign Up

Kalmarophen oral


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:

Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

When these two medicines are taken together, the barbiturate may cause your body to process the blood-thinner more quickly.

What might happen:

The effect of the blood-thinner may decrease.There is an increased chance of bleeding if you are taking these medicines together and you stop taking the barbiturate. You may experience bleeding from your gums, nose bleeds, unusual bruising, or dark stools.

What you should do about this interaction:

Contact your healthcare professionals (e.g. doctor or pharmacist) as soon as possible about taking these two medicines together. If your doctor prescribes these medicines together, you may need to check your bleeding times more often.Your healthcare professionals 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.Levy G, O'Reilly RA, Aggeler PM, Keech GM. Pharmacokinetic analysis of the effect of barbiturate on the anticoagulant action of warfarin in man. Clin Pharmacol Ther 1970 May-Jun;11(3):372-7.
2.Goss JE, Dickhaus DW. Increased bishydroxycoumarin requirements in patients receiving phenobarbital. N Engl J Med 1965 Nov 11;273(20):1094-5.
3.MacDonald MG, Robinson DS. Clinical observations of possible barbiturate interference with anticoagulation. JAMA 1968 Apr 8;204(2):97-100.
4.Lucas ON. Study of the interaction of barbiturates and dicumarol and their effect on prothrombin activity, hemorrhage, and sleeping time in rats. Can J Physiol Pharmacol 1967 Sep;45(5):905-13.
5.Aggeler PM, O'Reilly RA. Effect of heptabarbital on the response to bishydroxycoumarin in man. J Lab Clin Med 1969 Aug;74(2):229-38.
6.Breckenridge A, Orme M. Clinical implications of enzyme induction. Ann N Y Acad Sci 1971 Jul 6;179:421-31.
7.Johansson SA. Apparent resistance to oral anticoagulant therapy and influence of hypnotics on some coagulation factors. Acta Med Scand 1968 Oct;184(4):297-300.
8.Welch RM, Harrison YE, Conney AH, Burns JJ. An experimental model in dogs for studying interactions of drugs with bishydroxycoumarin. Clin Pharmacol Ther 1969 Nov-Dec;10(6):817-25.
9.Antlitz AM, Tolentino M, Kosai MF. Effect of butabarbital on orally administered anticoagulants. Curr Ther Res Clin Exp 1968 Feb;10(2):70-3.

Be the first to share your experience with this drug.

Review this Treatment

Find a Drug:

by name or medical condition or shape/color (Pill Identifier)

(for example: aspirin)

(for example: diabetes)

Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Ask the pharmacist

Questions about medications? Get expert answers by video or live chat about allergies, pregnancy, sleep, and more.
See the Ask the Pharmacist event schedule.

Ask a Question

Popular Slideshows & Tools on WebMD

hands on abdomen
Can you catch one?
Woman sitting in front of UV lights
Is yours working?
woman using breath spray
What's causing yours?
womans hand on abdomen
Are you ready for baby?
MS Overview
Recognizing symptoms.
bowl of yogurt with heart shape
Eat for a healthy heart.
woman doing pushups
To help you get fit.
Colored x-ray of tooth decay
Know what to look for.
Woman sitting with child
Do you know the symptoms?
Stings, bites, burns, and more.
Allentown, PA
Are you living in one?
Thyroid exam
See how much you know.

Women's Health Newsletter

Find out what women really need.

WebMD the app

Get trusted health information. Whenever. Wherever... with your iPhone, iPad or Android.

Find Out More

IMPORTANT: About This Section and Other User-Generated Content on WebMD

The opinions expressed in WebMD User-generated content areas like communities, reviews, ratings, or blogs are solely those of the User, who may or may not have medical or scientific training. These opinions do not represent the opinions of WebMD. User-generated content areas are not reviewed by a WebMD physician or any member of the WebMD editorial staff for accuracy, balance, objectivity, or any other reason except for compliance with our Terms and Conditions. Some of these opinions may contain information about treatment or uses of drug products that have not been approved by the U.S. Food and Drug Administration. WebMD does not endorse any specific product, service, or treatment.

Do not consider WebMD User-generated content as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare provider because of something you have read on WebMD. You should always speak with your doctor before you start, stop, or change any prescribed part of your care plan or treatment. WebMD understands that reading individual, real-life experiences can be a helpful resource but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified health care provider. If you think you may have a medical emergency, call your doctor or dial 911 immediately.