Drug Interaction Checker

A drug interaction occurs when another substance changes how a medication works, possibly increasing side effects or changing its effectiveness. Common substances that can interact include prescription and over-the-counter drugs, alcohol, food, drinks like grapefruit juice, herbal or dietary supplements like St. John's Wort and health conditions, according to the U.S. Food and Drug Administration (FDA).

There are 3 main types of drug interactions to watch for:

Drug-drug interactions: This is the most common type of drug interaction and involves one drug interacting with another. If you take many medicines, your chances for this type of interaction increases. For example, taking two medicines that cause drowsiness at the same time - like the pain treatment oxycodone and the muscle relaxer cyclobenzaprine (brand name: Amrix) - can increase this side effect.

Drug-food and drug-beverage interactions: Food and drinks can change how medicines work or worsen side effects when they are combined. Examples include beverages like grapefruit juice and statins causing muscle pain, or alcohol and opioids leading to dangerously slowed breathing.

Drug-disease interactions: Your medical conditions can affect the way a drug works or lead to side effects. For example, taking a nasal decongestant like pseudoephedrine if you have high blood pressure may worsen this condition. If you have liver disease, using the common pain and fever reducer acetaminophen (Tylenol) may be toxic to your liver.

The signs and symptoms of a drug interaction can vary widely, and may include nervous system side effects like drowsiness, dizziness, confusion, or depression. Heart effects, like a slow or fast heart rate or low blood pressure might occur. Stomach side effects, like stomach pain, nausea or vomiting, or diarrhea are common.

Other effects could include a skin rash, weakness, nausea or vomiting, diarrhea, muscle or joint aches, incontinence, falls, increased bruising or bleeding, anxiety or reduced effectiveness of your medicine.

Some symptoms due to a drug interaction may be minor, while others can be serious or life-threatening. As reported in the journal Drugs and Aging, some factors that may increase your risk for serious drug interactions are older age, an increased number of drugs prescribed or number of doctors, and a frail medical condition.

If you think you may be experiencing a symptom or side effect due to a drug interaction, contact your healthcare provider right away for advice.

To avoid a drug interaction be sure to tell your doctor, pharmacist and other healthcare providers about all the medicines you take, including prescription, over-the-counter, vitamins, and herbal or dietary supplements. Let them know if you drink alcohol or grapefruit juice, and have your pharmacist check for drug interactions any time you start or even stop a medicine.

Because you may not know if your medicines have any drug interactions, it's important to check for them before you start treatment. Ask your doctor or pharmacist to check your drugs for any important drug interactions. Discuss if you need to have your kidney or liver function checked before starting a new treatment.

Learn how to recognize the effects and what you should do if you think you are having a serious drug interaction. In case of a drug interaction, learn when you should call your doctor or 911 for emergency help.

Drug interactions are a major cause of hospitalizations and side effects. A 2024 study in Scientific Reports found that 5% of 287 hospitalizations (median patient age 78 years) were caused by side effects associated with factors like multiple medication use (polypharmacy), age over 65 years and use of an ambulance.

Other tips on how to avoid drug interactions include keeping a list of medicines with you that you can show at the pharmacy and at medical appointments, learning why you are taking your medicine, and if your medication interacts with alcohol, food or drinks, or any medical conditions you may have.

Over-the-counter (OTC) medicines also contain a Drug Facts Label that helps to explain the medicine. Read this information carefully. If you do not understand your directions, ask a healthcare professional for help.

All medicines come with written instructions. Follow those directions closely.

To determine if your medicine has an interaction with grapefruit juice, you can check with your doctor or pharmacist. Many medicines have this interaction, so it's important to ask about this interaction if you eat grapefruit or drink the juice. In some cases it will cause the levels of drugs to increase in the blood, which can cause side effects.

Drug interactions with grapefruit juice are important because they can occur with common medicines, like statins used to help lower cholesterol, drugs that help lower blood pressure or even treatments that fight cancer, as reported by the FDA.

Your prescription bottle or other written information will explain if you should avoid grapefruit juice with your medicine. Your pharmacist may attach a special sticker to your bottle, or it may be found in printed instructions they give to you.

Many medicines have interactions with food and drinks. Other juices, like orange juice or pomegranate juice, can interfere with some medicines, but this is less common than grapefruit juice. If you have any questions about food or drink interactions with your medicines, your pharmacist is a great resource.

To learn more about this topic, read the article Drug interactions with Grapefruit Juice - What to Know.

Many medicines can have an interaction with alcohol found in wine, beer, liquor or other medicines. Mixing drugs like pain medicines, sleeping pills or anxiety treatments with alcohol can be unsafe or even deadly due to increased sedation, confusion or slowed breathing, which may be fatal.

Be sure to check your prescription drugs, as well as your over-the-counter medicines, herbals, and dietary supplements like vitamins and minerals for alcohol interactions. Some cough and cold medicines may also contain alcohol, so be sure to check the labels.

Alcohol is itself a drug and may cause side effects like drowsiness, dizziness or fainting. When you combine it with other drugs that have similar side effects, your breathing may slow to dangerous or deadly levels. You might become unsteady and be at risk for a fall or broken bone. Extra drowsiness can make it very dangerous for you to drive or perform hazardous activities.

Alcohol can also change the way another drug works. For example, it may slow down or speed up how quickly a drug leaves your body. This can affect how well the drug treats your medical condition or if it causes toxicity.

Use of alcohol with medicines can be especially harmful in older patients, who may take several interacting medicines. A peer-reviewed study by Breslow and colleagues found that in the previous year among drinkers, about 43% of adults and 79% of people aged 65 and older took a medication that could interact with alcohol.

These interactions might interfere with your successful treatment or cause dangerous side effects. Always check to see if your medicines interact with alcohol before you combine the two.

Continue reading: Drug and Alcohol Interactions - What to Avoid

Herbal drug interactions can be just as serious as with prescription medicines. For example, St. John's Wort, Coenzyme Q10, and melatonin can interact with medicines like antidepressants, blood thinners or alcohol, according to the National Institutes of Health.

Common herbal supplements that may lead to potential interactions include Asian Ginseng, Cat's Claw, Chamomile, Cranberry, Ginkgo, Goldenseal, Green Tea and St. John's Wort, according to the National Center for Complementary and Integrative Medicine.

Herbs and dietary supplements can be purchased over-the-counter (OTC) and may be labeled "all-natural", but this does not always mean they are safe. Because there's not always formal studies, some drug interactions with herbal products may not be known. Also, remember that herbal supplements are not subject to FDA review and have not usually been tested in clinical studies to prove their effectiveness or safety.

Up to one-third of adults in the U.S. may use herbal or dietary supplements for health reasons as published in a peer-reviewed study from the Journal of Patient Experience. Additionally, factors linked with herbal supplement use included age 70 years or older, education exceeding a high school level, using prescription or over-the-counter (OTC) medications, and utilizing a mail-order pharmacy.

Your pharmacist can give you a better idea of what drug interactions may occur with any herbal or dietary supplement you may be taking. Advice from your health care provider is your best option in preventing serious health effects from any drug interaction.

The article Herbal Supplements and Alcohol Interactions can provide additional information on this topic.

Checking with your healthcare provider is key in helping to prevent drug interactions.

You can also use the Drugs.com Drug Interaction Checker to learn more. This tool explains what the interaction is and how it occurs, the level of importance and how to handle the drug interaction. It will also display any interactions between your chosen medicines, alcohol, food, beverages, or medical conditions.

Keep an up-to-date list of your medications, over-the-counter products, vitamins, herbals, and medical conditions. Share this list with your doctor, pharmacist, and nurse at each visit so that they can also screen for possible drug interactions.

Ask your doctor if you take any high alert or narrow therapeutic index drugs, such as chemotherapy (cancer) drugs, warfarin, or digoxin. According to the National Center for Complementary and Integrative Medicine, you may be at greater risk for serious drug interactions.

Information is available for you to read, too. Review the Medication Guide, patient prescription information, warning labels, and OTC Drug Facts Label supplied with each new prescription or over-the-counter product you buy.

Information may change as new information is learned about medications, so it's important to review the information frequently. Ask your pharmacist if you need a copy of any of this information.

It's important to promptly address any drug interactions that you suspect. Call your doctor or pharmacist right away if you think you are at risk for a drug interaction. They will know if the interaction is serious and can recommend the next best steps. Older people, those who take multiple medications and people with numerous medical conditions should be especially careful.

Luckily, most drug interactions can be prevented because your provider and pharmacist can review for these before you start your medicine. Be sure not to stop taking any medicines without your doctor's approval first.

Be sure to let your healthcare team know about all of the medicines you take, including prescription drugs, OTC medicines, vitamins, and herbal and dietary supplements. If you are pregnant, planning a pregnancy or breastfeeding you should always check with your healthcare provider before taking any medicine or substance.

If you have questions, be sure to ask your healthcare team.

Related: Top 9 Ways to Prevent a Deadly Drug Interaction