6 Disulfiram Interactions to Watch Out For

If you or a loved one has alcohol use disorder (AUD), you may have heard of a medication called disulfiram. It’s also known as Antabuse, but this brand-name product has been discontinued. While disulfiram has been around for many years, it’s not a first-choice treatment option for AUD. But it’s still a good option for some people.

If you’re prescribed disulfiram, there’s several things to keep in mind. This includes how to take it, its possible side effects, and the potential drug interactions. In this article, we’ll focus on disulfiram interactions — why they happen and how to prevent or manage them.

1. Alcohol

Disulfiram interacts with alcohol. In fact, this interaction is the basis of how disulfiram works. If you drink alcohol while taking disulfiram, you’ll experience the “disulfiram-alcohol reaction.” This is an unpleasant reaction that’s intended to discourage you from drinking alcohol. 

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Symptoms of the disulfiram-alcohol reaction may include:

• Flushing

• Sweating

• Nausea and vomiting

• Heart palpitations

• Low blood pressure

The more alcohol you consume, the more intense these symptoms are. For most people, the symptoms improve within about an hour. But in rare cases (usually if large amounts of alcohol are consumed), the symptoms can last for several hours or become life-threatening.

To avoid the disulfiram-alcohol reaction, don’t drink alcohol while you’re taking disulfiram. In fact, you should avoid alcohol for 12 hours before taking disulfiram. Otherwise, some alcohol may still be in your system and can cause a reaction with disulfiram. 

Contact your prescriber if you think you’re experiencing the disulfiram-alcohol reaction. If you have severe symptoms like fainting, extreme dizziness, or trouble breathing, go to the nearest emergency room or call 911.

2. Alcohol-containing products

Several household products, foods and drinks, and medications contain small amounts of alcohol. But even small amounts can cause the disulfiram-alcohol reaction discussed above. Examples of products that may contain alcohol include:

• Over-the-counter (OTC) medications, such as some forms of NyQuil

• Skin products, such as some hand sanitizers, aftershaves, perfumes, colognes, and nail polish removers

• Some mouthwashes, mints, and toothpastes

• Certain foods and drinks, like some vitamin-infused drinks, sauces, extracts, and vinegars

• Non-alcoholic beers, which may still contain very small amounts of alcohol

Always check product labels if you take disulfiram. Specifically, look at ingredient lists to see if ethanol or ethyl alcohol is listed. Also, look for the names of sugar alcohols like sorbitol, xylitol, and erythritol. Avoid any products that contain these ingredients.

Additionally, check with your pharmacist or prescriber before taking OTC medications, especially liquid products, with disulfiram. They can help you determine whether an OTC medication contains alcohol and may be unsafe to use.

3. Phenytoin

Phenytoin (Dilantin, Phenytek) is a medication that helps prevent and treat seizures. Taking the right phenytoin dosage is key to the medication working properly. It also helps you avoid unwanted side effects. This is why your prescriber will check your blood levels of phenytoin regularly.

Disulfiram can increase phenytoin levels, potentially leading to phenytoin toxicity. Symptoms of phenytoin toxicity may include excessive tiredness or fatigue and sudden confusion. If the case is severe, you could experience seizures or coma.

If you need to take both phenytoin and disulfiram, your prescriber will monitor your phenytoin levels closely. This is especially important when you first start taking the medications and if your dosages change.

4. Blood thinners

Blood thinners refers to both anticoagulant and antiplatelet medications. These medications decrease your risk of getting blood clots, but they’re used in different situations. Examples of anticoagulants are Eliquis (apixaban), Xarelto (rivaroxaban), and warfarin (Coumadin, Jantoven). Examples of antiplatelets are Plavix (clopidogrel) and low-dose aspirin.

Because they prevent clotting, blood thinners can increase your risk of bleeding. And disulfiram has been shown to increase the amount of time it takes your blood to clot. Combining these medications could increase bleeding more so than taking blood thinners on their own.

If you take a blood thinner, it’s probably an important part of your medication regimen. So you may not be able to stop taking it, even if you’re prescribed disulfiram. In this case, your prescriber may monitor you more closely, especially when starting or stopping treatment with disulfiram. 

You should watch for signs of bleeding like bleeding gums, unusual bruising, and blood in the urine or stool. If you experience any unusual bleeding or bruising, contact your prescriber immediately. If you experience bleeding that doesn’t stop, seek emergency care.

Keep in mind that disulfiram and blood thinners may be prescribed by different healthcare professionals. Make sure your entire care team knows what medications you take. Having all of your healthcare professionals watching out for potential drug interactions can help keep you safe.

5. Isoniazid

Isoniazid is an antibiotic that prevents and treats tuberculosis. Isoniazid may increase blood levels of disulfiram. And older research has indicated that the combination can change the balance of chemicals in your brain, leading to changes in your behavior and ability to move normally. Though, keep in mind, there have been minimal studies of how disulfiram and isoniazid interact.

In fact, one small study suggests that the two medications actually don’t interact. However, it’s still wise to use caution if you take them together. And be sure to report any changes in mood or mental status to your prescriber. 

6. Metronidazole

Metronidazole (Flagyl) is an antibiotic that treats a variety of infections. When combined with disulfiram, it can cause symptoms of psychosis, including hallucinations. Other symptoms of medication-induced psychosis include disorganization, confusion, and delusions (believing something that clearly isn’t true). 

The reason this reaction occurs may be because both medications can increase a brain chemical called dopamine. Too much dopamine can cause the psychosis symptoms discussed above. Psychosis can also happen if you take large amounts of disulfiram.

If you’re taking disulfiram, make sure all of your healthcare professionals know. This way, they can avoid prescribing you metronidazole for a bacterial infection. Metronidazole should be avoided for at least 2 weeks after your last disulfiram dose. 

When should you contact your healthcare team about disulfiram interactions?

Ideally, your healthcare team can help you avoid disulfiram interactions upfront. But in some cases, you may need to take disulfiram with a medication that it may interact with.

To get ahead of disulfiram interactions, give your prescriber and pharmacist a current list of your medications. This will help them screen for interactions before you start taking disulfiram. If there is a potential interaction, they can tell you what symptoms to watch out for. For example, if you take a blood thinner with disulfiram, you’ll want to watch out for unusual bruising or bleeding. If you take any OTC medications, ask your pharmacist to check them for alcohol. Check the foods you eat and any skin or hair products you use, too.

If you have severe symptoms of a disulfiram reaction, like bleeding that won’t stop or severe drowsiness, seek emergency care.

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Written by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

Edited by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Soojin Jun, PharmD, BCGP

Soojin has 10 years of experience in various pharmacy settings, from inpatient to outpatient settings, and population health in value-based healthcare models. She completed training in various areas of healthcare to ensure patient safety, from activism, geriatric pharmacy, medication safety, healthcare quality, patient safety, death and dying, and trauma-informed care.

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