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topical cbd oil and warfarin

Products containing cannabidiol (CBD) seem to be all the rage these days, promising relief from a wide range of maladies, from insomnia and hot flashes to chronic pain and seizures. Some of these claims have merit to them, while some of them are just hype. But it won’t hurt to try, right? Well, not so fast. CBD is a biologically active compound, and as such, it may also have unintended consequences. These include known side effects of CBD, but also unintended interactions with supplements, herbal products, and over-the-counter (OTC) and prescription medications.

Many drugs are broken down by enzymes in the liver, and CBD may compete for or interfere with these enzymes, leading to too much or not enough of the drug in the body, called altered concentration. The altered concentration, in turn, may lead to the medication not working, or an increased risk of side effects. Such drug interactions are usually hard to predict but can cause unpleasant and sometimes serious problems.

Doubling up on side effects

CBD has the potential to interact with many other products, including over-the-counter medications, herbal products, and prescription medications. Some medications should never be taken with CBD; the use of other medications may need to be modified or reduced to prevent serious issues. The consequences of drug interactions also depend on many other factors, including the dose of CBD, the dose of another medication, and a person’s underlying health condition. Older adults are more susceptible to drug interactions because they often take multiple medications, and because of age-related physiological changes that affect how our bodies process medications.

Absolutely. Inhaled CBD gets into the blood the fastest, reaching high concentration within 30 minutes and increasing the risk of acute side effects. Edibles require longer time to absorb and are less likely to produce a high concentration peak, although they may eventually reach high enough levels to cause an issue or interact with other medications. Topical formulations, such as creams and lotions, may not absorb and get into the blood in sufficient amount to interact with other medications, although there is very little information on how much of CBD gets into the blood eventually. All of this is further complicated by the fact that none of these products are regulated or checked for purity, concentration, or safety.

People considering or taking CBD products should always mention their use to their doctor, particularly if they are taking other medications or have underlying medical conditions, such as liver disease, kidney disease, epilepsy, heart issues, a weakened immune system, or are on medications that can weaken the immune system (such as cancer medications). A pharmacist is a great resource to help you learn about a potential interaction with a supplement, an herbal product (many of which have their own drug interactions), or an over-the-counter or prescription medication. Don’t assume that just because something is natural, it is safe and trying it won’t hurt. It very well might.

Opioids, such as hydrocodone/acetaminophen (Vicodin, Norco), oxycodone, (Oxycontin, Percocet) and fentanyl (Duragesic) are a powerful class of drugs used to treat pain that can be addictive. Research suggests that there is a relationship between the body’s opioids—endogenous, or naturally occurring opioids—and endocannabinoid system, although the exact mechanisms remain unknown.

CBD likely blocks the metabolism of these drugs in the liver—because of cytochrome P450—and causes the medication to exist in a higher level in the body and prolong its effects, 3 which can be toxic or cause other problems, such as excess bleeding or hemorrhage.

Cannabidiol (CBD) has become a popular treatment for back pain and other conditions.
Read:
CBD (Cannabidiol) for Chronic Pain

CBD and sedatives

One small study suggests that this interaction could help relieve pain and reduce opioid use when used together. 4 However, more research should be done on this topic.

Drugs used to thin blood, such as warfarin (Coumadin), and drugs that carry an increased risk of bleeding, such as ibuprofen (Advil) or naproxen (Aleve), have been shown to interact with CBD.

The exact relationship between sedatives and CBD is unknown, however, high doses of cannabinoids may have an unwanted additive effect, and the two likely should not be used together.

Many medications, such as those used to treat high blood pressure or fight off infection, come with a warning to avoid grapefruit juice and similar products. This is because grapefruit inhibits the activity of a group of liver enzymes (where many drugs are metabolized or broken down by the body) called cytochrome P450. Cannabidiol also inhibits the activity of cytochrome P450, 1 which means that it can alter the way the body metabolizes different drugs—either causing there to be too much or too little in the system.