I'm a Pharmacist, and This Is the Medication I Always Warn Patients About

Any time you start a new medication, you should always discuss it with a trusted medical professional. According to Tessa Spencer, PharmD, a specialist in community pharmacy and functional medicine, this conversation should include how to best take the medication, how to avoid potential side effects, and what to do if they occur. However, some medications come with outsized risk, meaning your doctor or pharmacist will have important information for you to consider before you begin your new routine. Read on to learn which one medication Spencer often finds herself warning patients about, and which of its potentially serious side effects should be on your radar.

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If you see this on a drug label, your medication may come with serious side effects.

While any drug can come with side effects, Spencer notes that some classes of medication tend to have more serious side effects than others. 'These medications have what are called 'black box warnings,' which are required by the U.S. Food and Drug Administration (FDA) to indicate rare, but dangerous side effects," she explains. Commonly prescribed medications such as antipsychotics, antidepressants, opioid painkillers, blood thinners, and others often come with black box warnings, she explains.

"It's important to note that black box warnings do not necessarily mean you shouldn't take the medications that have them," says Spencer. However, you should take extra care to discuss your prescription's potential risks with your doctor or pharmacist if you see this on the label.

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This is the medication Spencer always warns patients about.

Spencer says that the one "black box" medication she finds herself counseling patients on "extra carefully" is the anticoagulant blood thinner warfarin, also sold under brand names Coumadin and Jantoven. "Warfarin is used to prevent and treat blood clots and to lower the chance of heart attack or stroke in certain individuals. While warfarin is one of the most effective medications to prevent blood clots, it also comes with a whole host of rules and restrictions for the patient," she says. "If a patient doesn't follow these rules, serious side effects can occur."

Spencer explains, for example, that it's important for those taking Warfarin "to have their blood checked periodically to ensure the time it takes for the patient's blood to clot is within a small target range. This target range can be affected by many things; prescribed or over-the-counter medications, when warfarin is taken during the day, dietary patterns, alcohol consumption, and illness. Any of these might lower the effectiveness of warfarin or increase the risk of bleeding."

These are some of its most concerning side effects.

Warfarin requires extra counseling due to its potential to cause internal bleeding, Spencer says. "In the same way warfarin prevents blood clotting, it can also cause bleeding. A cut on your hand or nosebleed may be difficult to stop if you're taking warfarin. But the most serious side effect healthcare professionals worry about is bleeding inside the body or internal bleeding," she notes.

She adds that since internal bleeding is not visible, it can go undetected until patients begin to develop life-threatening symptoms. "That's why it's important to monitor warfarin therapy and perform blood tests on patients taking [the drug]," Spencer advises.

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These alternatives may put you at lower risk of side effects.

Spencer says there are now several other blood thinners on the market which may be prescribed to help lower heart attack or stroke risk. These include Eliquis (apixaban), Pradaxa (dabigatran), Xarelto (rivaroxaban), and Savaysa (edoxaban). "Unfortunately, they all have some risk of bleeding due to their ability to thin the blood," she concedes. However, she adds that "the risk of excessive bleeding is less with these new medications, and may not be as serious if it does happen."

Additionally, Spencer says these alternative medications may also be "more convenient to take, as patients don't need as many blood tests." Speak with your doctor if you have been prescribed warfarin and have questions about your care, or if you have experienced any side effects while taking it.

Best Life offers the most up-to-date information from top experts, new research, and health agencies, but our content is not meant to be a substitute for professional guidance. When it comes to the medication you're taking or any other health questions you have, always consult your healthcare provider directly.