The All-In-One Guide to Drug Interactions


We are lucky enough to live in a time where lots of incredible drugs exist to cure the most serious conditions that remain untreatable in the past. As stated by the CDC or the Center for Disease Control and Prevention, approximately 48.7% of Americans have been taking at least one prescription drug over the last 30 days and about 21.8% of Americans use up to 3 or more prescriptions. It’s uplifting to know that there are now plenty of treatment options that can help to cure some of the most common ailments. However, the impressive availability of the different medications has also resulted in the increased risk of drug interactions.

Drug interactions refer to the combination of some drugs with other substances, which alters the medicine’s effect on the body. This could cause the medications to be more or less potent than intended. These combinations can also lead to unexpected side effects in the body, and others are harmful.

If you’re going to take different kinds of medications and you’re suffering from certain health conditions, you have to be especially mindful of these different kinds of medications. You must also make sure that your doctors are aware of all the drugs, supplements, herbs, and vitamins that you’re taking. Even if you were only taking one medication, it would be best to talk to your doctor regarding the drugs you’re using so they can identify any possible interactions. This advice is useful to both non-prescription and prescription drugs.

Drug Interactions Types

Drug-Drug.  This is an interaction in between two drugs or more. It could involve over the counter medications, prescription medications, supplements, vitamins, and herbs. One example is a patient who is taking a diuretic, a type of drug that works by getting rid of the excess water and salt in the body. Yet, this patient also takes Ibuprofen and this medication could reduce the effectiveness of diuretics since ibuprofen can make the body to retain fluid and salt.

Drug-Food. This happens when the beverage and food consumption alters the effect of the medication. Perhaps, you’re taking certain statins to help lower your cholesterol, yet you drink plenty of grapefruit juice, this could end up with too much drug staying the body and could increase your chances of developing kidney failure or liver damage.

Drug-Alcohol. This is when a certain type of medications must not be taken along with alcohol. Usually, combining these two could lead to tiredness and delayed reactions. This could also increase your chances of suffering from several harmful side effects.

Drug-Disease. This is when you are taking a particular drug that could alter or worsen your condition. For instance, a decongestant that some people take to cure colds could lead to an increase in blood pressure. This is potentially dangerous especially for people who are suffering from hypertension or high blood pressure.

Drug-Laboratory. This is when a medication would interfere with a lab test. This could lead to inaccurate test results. For example, a certain type of antidepressants is known to interfere with the skin prick test, a type of test used to determine a possible allergic reaction.

Other Factors in Drug Interactions

It is important that you are aware of the possible interactions with the drugs you are taking. However, just because a possible drug interaction could take place does not really mean that it will happen in every instance. There are lots of factors that could affect a drug’s interaction and whether its side effects will be harmful or not. Specifics about certain drugs, including the formulation, dosage, and the way you take them could certainly make a huge difference.

Considerations regarding personal medical history:

Genetics. Variations among each individual’s genetic makeup can also make certain types of drugs to work differently in different person. Because of a certain genetic code, some people tend to process particular medications more slowly or quickly than others, which could make the drug levels to increase or decrease. Your doctor is aware of which particular drug would require genetic testing in order to determine the right dose for you.

Weight.  Certain drugs are dosed according to a patient’s weight, while other drugs are not. This could also affect your risk of possible drug interactions. If you have undergone a significant change in your body weight, you’ll need different doses of certain medications.

Age.  As we grow older, our bodies also change in many ways and this could affect how our body would respond to certain medications. Our liver, kidneys, and the circulation system could slow down as we get older and this could also slow down the drug’s breakdown and removal in our body and will affect how long the drug could linger in our body.

Gender. The gender differences, such as the hormones and anatomy of a person, can also play an important role in the drug interactions. For instance, a dose of Ambien (Zolpidem) that was prescribed to a woman is lower than the dose prescribed for a man. This is because it was found through research that women are more likely to end up with higher levels of this drug in their system early in the morning and could prevent them from doing certain activities such as driving.

Lifestyle. There are certain types of diets that could become a problem if combined with certain medications. For instance, research shows that a high intake of fat could reduce the body’s response to bronchodilators, a medication that people with asthma often take. Exercise may also alter the way the medications would work in the body. For instance, people who are using insulin in treating their diabetes could suffer from hypoglycemia or low blood sugar when exercising may need to modify the time that they eat and take the insulin so as to offset the drop in their blood sugar level.

How Long the Drug Will Stay in the Body.  A lot of factors could affect the speed at which the body will be able to absorb and process certain types of medications. The right dose of medication [Inserted: s]for each person will usually depend on these and it could be lower or higher than the usual dose. This is also one of the reasons why your doctor should know all the medications that you are taking before he or she can prescribe you with a new medication.

How Long You’ve Been Using the Drug.  The body could tolerate certain medications over time or the drug itself could help the body to process the medicines more quickly as time goes by. The doses can be adjusted if the patient is taking it for a long time already. Examples are anti-seizure medications and pain drugs.

Drug Factors You Should Consider

It is important that you are aware of the possible interactions with the drugs you are taking. However, just because a possible drug interaction could take place does not really mean that it will happen in every instance. There are lots of factors that could affect a drug’s interaction and whether its side effects will be harmful or not. Specifics about certain drugs, including the formulation, dosage, and the way you take them could certainly make a huge difference.

Dose. Dose is basically the number of drugs prescribed by the doctor to be taken at a certain period of time. Two people taking similar drug may be prescribed with different doses. Determining the proper dose requires some prescription so patients must not alter their dosage without the advice of their doctor.

How the Drug is Taken.  There are several different ways in which a medication can be administered. Most of the time, the drugs are taken orally (by mouth). There are also some drugs that are applied topically (through the skin) and rectally (through the rectum). The manner in which the medications get into the body could greatly affect the resulting effects.

Formulation.  The drug’s formulation is basically the specific combination of ingredients that the drug is made of. The drug’s formulation is very important since it could determine how the drug acts in the body and its effectiveness as well.

The Order in Which the Drugs Are Taken. Certain drug interactions can be lowered or totally eliminated if two medicines are taken at different period of times. There are also certain medications that could affect the manner in which other drugs are absorbed by the body. Antacids such as calcium tablets could also prevent the absorption of antifungal drugs, such as ketoconazole.

Reading Drug Labels

Consulting with your pharmacist or doctor is one way to get updated regarding your medications, although it’s also a good idea to take time to read and understand drug labels, whether the drugs are OTC or not. Doing so can help in better understanding the drugs and can also help to prevent any interactions.
Sections of an Over the Counter drug label:Active Ingredient and Purpose: This is the listing of the ingredients of the drug that have therapeutic purposes. The purpose section will indicate what each ingredient can do, whether it’s a nasal decongestant, etc.

Directions. These are instructions on how much of the drug must be taken and the number of times it has to be taken. If there are any special instructions on how the drug is to be taken, then that will also be included here.
Inactive Ingredients: This lists the ingredients that don’t serve any therapeutic purposes, like flavorings, colorings, etc.
Other Information. This part lists information on how the drug has to be stored properly. It will also provide details about the ingredients that the drug is made of, such as sodium, calcium, potassium, etc.

Uses. This is a short description of the conditions or symptoms that the particular drug is meant to cure.
Warnings: This indicates the important tips about how to safely use the drug. It will also include information on when to stop, when to consult a doctor, etc. It may also include the potential interactions and side effects of the following drug.

Manufacturer Contact Information. If you need to call the manufacturer for questions or assistance, this is where you’ll find their contact information.

Prescription Drug Labels

There are usually two types of prescription labels. The full label is indicated in the package insert and has a long detailed document about the drug’s information. This is often found inside or attached in the prescription.

The other type of prescription label is easy for patients to understand and is attached to the drug’s packaging or bottle. This label includes the name of the medication, the doctor’s name, patient’s name, the dosage of the medicine, special instructions, and some other important information. The brief information is intended to remind you of the proper way of taking the drug. Prescription vial also includes warning labels that come in the form of colorful stickers attached directly on the bottle or packaging of the medication.

Each of the new prescription lists down the patient information regarding the use of the drug, which is often written more visibly than the other package inserts. This information is usually personalized and includes the patient’s name.

The standards and format of both the prescription and package inserts through labels are usually agreed upon and set by USP or the United States Pharmacopeia. This is a volunteer organization that sets standards for pharmacy. In addition, each and every state has a board of pharmacy that details the pharmacy procedures including the labeling of the medication’s prescriptions.

In order to learn more about the prescription drug, it may be a good idea to ask for the package insert. This usually includes a summary section that’s mainly intended for the patients. The package insert will also describe the medicine and includes some other important details, such as:

  • How the drug is taken and any important precautions.
  • How the medicine works including other information about clinical tests done for the drug.
  • Information about the proper dosage including instructions on what needs to be done in the event of a drug overdose.
  • Other important information such as how to store the drugs, etc.
  • Possible interactions with other medications, supplements, beverages, and food.
  • The conditions that the drug is expected to treat.
  • Warnings regarding any adverse reactions and possible side effects.

Food-Drug Interactions

Grapefruit is known as the forbidden fruit when it comes to taking medications. This is especially applicable to people taking one of the many drugs that the grapefruit is known to interact with. The fruit contains a chemical compound that keeps an enzyme from metabolizing the drugs, which includes the cholesterol-lowering statins like the simvastatin. This leaves them free to reach the level that’s potentially toxic. Other citric fruits like limes and oranges are also said to lessen the body’s ability to absorb certain drugs.

Calcium, which is found in most dairy products including yogurt, cheese, and milk, may also have a similar effect in terms of absorbing tetracycline, a type of antibiotic that’s used for treating a wide range of conditions.

Certain types of cheese may also interact with the MAOI or Monoamine Oxidase Inhibitors, a first-class antidepressant drug. A British pharmacist discovered this when his wife took the MAOI. In his observation, whenever his wife would eat something that has cheese, she would end up with severe headaches. This interaction is a result of the tyramine, a type of enzyme found mostly in aged cheese. He later found that the combination of this enzyme to cheese could result in hypertensive crisis, a condition that refers to a dangerous spike in the level of blood pressure that could potentially lead to stroke.

In terms of food and drug interactions, those who are taking warfarin, a type of blood thinner that’s used to treat conditions like atrial fibrillation and deep vein thrombosis, should be extremely careful. This medicine is known to react with several foods, including supplements and some other drugs. Vitamin K could help the blood clot, which is an important mechanism in treating wounds, but this is the exact opposite of how warfarin should work. Therefore, foods that are rich in Vitamin K like spinach, cabbage, and kale could reduce the medication’s effectiveness and could increase one’s risk of stroke and dangerous blood clots.

Supplement-Drug Interactions

Even though Vitamin K is found mostly on leafy greens, one may also take it in the form of a supplement and he or she should be aware of similar interactions. This also holds true for potassium. The heart, brain, and kidney are three major organs in the body that the potassium can help, which makes it a popular supplement. But when taken along with angiotensin converting enzymes, a drug used for treating high blood pressure, too much of potassium will have the potential of causing heart palpitations. In the more extreme cases, this could become life-threatening.

As mentioned previously, warfarin is especially susceptible to food and drug interactions and the same holds true for supplements. Garlic, ginseng, and St. Jon’s wort, are just some of the supplements that have the possibility to react with warfarin leading to potentially serious side effects.

Drug-Drug Interactions

Drugs may also interact with another drug. Although your doctor will normally check for any drug interactions in between the medications that he prescribes you to take, this may not be possible if you’re going to take medications that you acquire over the counter. Yet, several OTC medications are actually known to cause harmful side effects if taken along with some other drugs.

Nasal decongestants are among those drugs that some patients don’t think twice about taking when remedying a cold, could interact with some hypertension medication and could potentially lead to an increase in the level of blood pressure.

Antihistamines are also among the most common go-to medications that have the potential to increase blood pressure, especially for those taking hypertension medication. In addition, antihistamines could lead to excessive sleepiness and this could severely impair one’s level of concentration if taken along with tranquilizers and sedatives

How to Avoid Drug Interactions

With every drug that you take daily, your risk of drug interactions will also increase. Since more than one in ten Americans are said to have taken more than five medications within a month, it might seem like drug interactions cannot be avoided. However, there are some simple steps that one can follow in order to avoid the risk of drug interactions.

Use the Same Pharmacy. Most pharmacies have automated systems in place that could flag any risk for drug interactions. Your insurance company may also need to examine your claims of identifying possible clashes. Chain pharmacies usually keep digital records that are easy to check from different branches. Of course, pharmacies are able to get in touch with one another to gain information that they don’t have access to. Nevertheless, these systems are not free from any error so filling prescriptions, especially the newer ones, with the same pharmacy is the best way to check for any possible interactions. Using the same pharmacy also allows you to establish a good relationship with your pharmacist who can best advise you for any possible drug interactions.

Understand Your Meds. When taking medications, there’s really no such thing as too much knowledge. After you leave the pharmacy with your new prescription, you should ask yourself if you know anything about the drugs you are taking and if you’re aware of why and how you should take them. If the answer is no, then your possibility of complications resulting from drug interactions is increased. These same questions are also applicable when taking over the counter supplements and medications. If you’re in doubt, always talk to your doctor or pharmacist.

Know How to Take the Drug. It’s necessary to know if it’s safe for you to take your medication in an empty stomach or if you need to eat some food. For instance, if you’re taking Bisphosphonate, a class of drugs used to address bone loss, taking it with coffee, milk, or eating just about anything 30 min after taking the medicine could negate its effects. There are also some drugs that have to be taken with food, either to help in absorption or to keep them from irritating the lining of the stomach. There are also certain drugs that must not be taken along with certain food. The Tetracycline antibiotic, for example, must not be taken along with dairy products since calcium could interfere with the medicine’s ability to absorb.

Keep a Record. The more supplements and medications that you take, the more complicated it could become and the more prone you are to the complications of drug interactions. Therefore, it might be a good idea that you keep a record of the drugs you are taking and that includes prescription drugs, OTC pills, and supplements. You can use your smartphone in keeping track of all the drugs and pills you take.

Understand Food Interactions. Although there are certain foods that could possibly interact with medications, it doesn’t mean that you need to totally remove them from your diet. The key is in understanding the link between these foods and drugs and how you can avoid any possible interactions. It might just be a case of limiting your intake of a particular food or allowing a period of time either before or after you take the medicine. As with everything, the more knowledge you have about something, the better you would be able to manage the link between the food you eat and that of your medications.

Beware of Alcohol. One of the biggest risk factors for drug interactions is alcohol. In fact, it has the potential to provide adverse effects if combined with several OTC meds and prescription drugs. Yet, in a study done by the National Institute of Health, it was found that around 42% of adults in the United States who drink regularly are also taking medications that adversely interact with each other. While this does not really mean that every case resulted in serious complications, it’s possible that there’s an overlap in various cases. If you’re not really sure if a particular supplement or medication you take interacts with alcohol, it may be best to ask your doctor or pharmacist about it.
Complications resulting from drug interactions might be the reason behind the $30 billion adverse drug reactions cost in the United States economy every year, although this is a portion that can be possibly avoided by applying a few precautions. Most importantly, these precautions can help to ensure that your drugs would be able to work effectively for you and minimize the risk of dangerous complications and side effects.

Talk to Your Pharmacist. When you’re given a prescription, you could end up with as many as three different leaflets or sheets that list down your medication and each detailing the conditions that the drug is expected to treat, including how the drug must be taken, as well as its possible side effects. If you find the information to be too much for you to digest, your next step is to talk to your pharmacist and see if it’s possible for them to summarize the prescription for you.
Pharmacists possess an extensive knowledge of how certain drugs work, including their possible side effects. This also applies to supplements, medications, and the food that these drugs would possibly interact with. As a matter of fact, you may need to inform the pharmacist about the other prescription and non-prescription drugs you are taking when you pick your new prescription. If the pharmacist has identified possible interactions on any of the medications you’re taking, he or she will suggest a particular schedule for you to safely take them and minimize any possibility of interactions.
Your pharmacist might also be willing to discuss with your doctor regarding the possibility of adjusting the dosage of your medication or to look for another alternative that could work best for you. There are some health plans that come with medication therapy management, a program that allows for an in-depth discussion with pharmacists.

How Herbal Supplements Interact With Prescription Drugs

Over the centuries, people have been using complex properties obtained in plants in treating different kinds of illnesses. Now that modern prescription drugs are readily available, herbal supplements have become less popular although they are now slowly making a comeback as people are becoming more and more interested in natural and organic alternatives.

These natural supplements are usually taken along with prescription drugs, however, the combination could sometimes lead to some serious complications.

What Are Herbal Supplements?

Herbal supplements are made from ingredients that were obtained from the parts of a plant, such as flowers, bark, leaves, roots, and berries. They are available in different forms, from capsules, tablets, syrups, teas, powders, and creams. Most of the modern drugs of today are made from chemical compounds obtained in plants. For instance, morphine is obtained from the poppy plant and digoxin, which is a medicine for the heart, is made using a plant known as foxglove. Herbal supplements are usually self-prescribed and can be bought over the counter worldwide.

What Are the Potential Side Effects?

The side effects of taking prescription medicines along with the herbal supplements would vary from one situation to another although there are certain drug combinations that are dangerous. For instance, ginger, gingko, feverfew, and ginseng could lead to dangerous bleeding if they are used along with prescription drugs for blood thinners.

St. John’s Wort is also known to lessen the effectiveness of medications used for treating heart ailments, including anti-anxiety drugs, and HIV drugs. Furthermore, licorice is also said to lower the efficacy of heart rhythm medications and could increase the effect of diuretic medicines and this could drive the sodium and potassium to dangerous levels.

How to Limit the Risk of a Dangerous Interaction?

There are certain steps to take to minimize the risk of dangerous drug reactions when taking both prescription drugs and herbal supplements. Always consult with your pharmacist or doctor before you decide to take any herbal supplements, most especially if you just had a surgery, pregnant, or suffering from chronic illnesses.

Is Herbal Medicine Considered Safe?

A lot of people believe that products labeled as “all natural” are safe, but this is not always the case. Plant-based herbal supplements are also made of medicinal ingredients that could trigger unwanted side effects especially if they are taken in high dosage. Natural supplements are not regulated and manufacturers of these medicines are not required to indicate drug interaction warning on the labels of the products. Furthermore, any product recalls as a result of adverse drug interactions are only voluntary as of the moment.

Are Herbal Supplements Regulated by the FDA?

Herbal supplements or herbal medicines are recognized as dietary supplements. Although the FDA regulates these supplements, they don’t regulate them as medications. Some manufacturers of these drugs will have will need to undergo FDA approval before they can sell them in the market. Furthermore, the purity and quality of these herbals supplements would vary depending on the manufacturer and different batches of these supplements will also have varying quality.

Herbal supplements can be a safe and effective way to treat certain medical conditions for as long as they are used properly and as directed. However, it’s important to keep in mind that these supplements also contain powerful ingredients that could interact with the prescription drugs you are taking. As the popularity of herbal supplements continues to increase, it’s important that patients and doctors discuss it openly to prevent any dangerous side effects.

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