Check interactions with multiple drugs, vaccines, supplements, alcohol, food and diseases.
Not all drugs interact, and not every interaction means you must stop taking one of your medications. Always consult your healthcare provider about how drug interactions should be managed before making any changes to your current prescription.
Drug Interaction FAQs
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 can increase this side effect.
Drug-food and drug-drink 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 your high blood pressure.
The signs and symptoms of a drug interaction can vary widely. Some symptoms may be minor, while others can be serious or life-threatening.
Common signs or symptoms of a drug interaction may include:
- Drowsiness
- Dizziness
- Nausea or vomiting
- Diarrhea
- Muscle aches or pains
- Depression
- Increased bruising or bleeding
- Abnormal heart rate
- Skin rash
- Anxiety or restlessness
- Your medicine may not be working as well
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.
Because you may not know if your drugs have any interactions, it's important to check for them before you start treatment.
Here are some tips on how to avoid drug interactions:
- Let your healthcare provider know about all the prescription medicines you take, plus any over-the-counter (OTC) medicines, including vitamins, herbal or dietary supplements.
- It may be helpful to keep a list of medicines with you that you can show at the pharmacy and at medical appointments.
- Talk to your healthcare provider and pharmacist about your medicines. Learn why you are taking it, how often you take it, and if you should avoid taking it with other medicines, alcohol, foods or drinks.
- Ask your doctor or pharmacist to check your drugs for any important drug interactions. Learn how to recognize the effects of any drug interactions.
- In case of a drug interaction, learn when you should call your doctor or 911 for emergency help.
All medicines come with written instructions. Follow those directions closely. Over-the-counter 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.
More and more medicines have interactions with food and drinks. Grapefruit and other juices can interfere with some medicines. In many 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 occur with common medicines, like statins used to help lower cholesterol, drugs that help lower blood pressure or even treatments that fight cancer.
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. If you have questions about food or drink interactions with your medicines, your pharmacist is a great resource.
Continue reading: Common grapefruit drug interactions
Many medicines can have an interaction with alcohol, like wine, beer or spirits. This might interfere with your successful treatment or cause dangerous side effects. Mixing drugs like opioid pain medicines, sleeping pills or anxiety treatments with alcohol can be unsafe or even deadly. Always check to see if your medicines interact with alcohol before you combine the two.
Alcohol is itself a drug and may cause central nervous system 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 at risk for a fall or broken bone. Extra drowsiness can make it very dangerous for you to drive or perform hazardous activities.
Be sure to check your prescription drugs, as well as your over-the-counter (OTC) 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.
Continue reading: Drug and alcohol interactions - what to avoid
While herbs and dietary supplements can be purchased over-the-counter (OTC) and may be labeled "all-natural", this does not always mean they are safe. Many of these products, just like prescription drugs, may have serious drug interactions.
For example, St. John's Wort, CoenzymeQ10, and even melatonin can interact with medicines like antidepressants, blood thinners like warfarin or even alcohol. These interactions can be just as serious as prescription medicines.
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.
Your pharmacist can give you a better idea of what drug interactions may occur with any herbal or herbal dietary supplements you may be taking. Advice from your health care provider is your best option in preventing serious health effects from any drug interaction.
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, how it occurs, the level of importance and how to handle the drug interaction. It will also display any interactions between your chosen drugs, food, beverages, or a medical condition.
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.
Information is available for you to read, too. Review the Medication Guide, prescription information, warning labels, and Drug Facts Label with each new prescription or over-the-counter product you use.
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.
If you find you are at risk for an interaction, call your doctor or pharmacist. They will know if the interaction is serious and can recommend the next best step.
Luckily, most drug interactions can be prevented because your healthcare provider and pharmacist will screen for these before you start your medicine.
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. Be sure not to stop taking any medicines without your doctor's approval first.
Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on Oct 16, 2023.
