Taking Many Medicines and Wondering, “Is This Really Safe?”: Drug Interactions and Duplicate Prescriptions

Written by: 齋藤 直裕 (Pharmacist)

When a health problem interferes with daily life, or you worry about why you feel unwell, you see a doctor to find the cause. It’s fine if the cause is identified and removed and you return to your former condition, but when treatment takes time or a cure is difficult, medicine is used for a period to ease the symptoms. When a fundamental cure is difficult, medicine may be continued for even longer.

In Japan, many people now live long lives. With age, people increasingly have not just one health problem but several illnesses at the same time. Along with that, the number of medicines they use, and keep using, increases.

When you take many kinds of medicine, do you ever worry more about the medicines themselves than about treating your illness, wondering, “Is it really all right to take this many?” In fact, some people become anxious about how many medicines they take, or come to the pharmacy saying, “I can’t possibly take all of these.”

Interactions and duplication: problems that arise when you see several specialists

Many people who come to us worried about taking too many medicines see several different medical departments. Because they have more than one illness, they might, for example, see a cardiologist for weakened heart function while also seeing an orthopedic surgeon for a painful knee.

Under Japan’s health insurance system, there are rules about which medicines can be used for a given diagnosis, and prescriptions follow clinical practice guidelines based on extensive data and experience. When people worry about having too many medicines, the bigger issue is actually not the number of medicines but whether there are harmful reactions between them, known as drug interactions.

If you read the information leaflet and decide on your own to stop taking a medicine, it’s not just that your symptoms may not improve or the treatment may not work. If the doctor doesn’t know you’ve stopped, they may conclude that the medicine isn’t working and prescribe more, and you may fall into a vicious circle in which more and more untaken medicine piles up at home.

The first step is not to decide on your own, but to share your concerns about your medicines with your doctor or pharmacist.

What are drug interactions?

When several medicines are in the body, one medicine can affect the action of another. This is called a drug interaction. Think of it as a quarrel between medicines. One medicine may cancel out the effect of another, or it may strengthen the effect of another (making side effects more likely).

For example, suppose a cardiologist finds an arrhythmia (an irregular heart rhythm). An arrhythmia can impair blood flow, allowing clumps of blood called blood clots (thrombi) to form inside the blood vessels and block them. To prevent this, a blood-thinning medicine called warfarin may be prescribed.

When you get hurt and bleed, the bleeding doesn’t go on forever; the blood clots at the skin and stops. That is what forms a scab. The human body has more than one mechanism for clotting blood; many factors work together to stop bleeding. One of them uses vitamin K. Warfarin thins the blood by interfering with the action of vitamin K.

Vitamin K, however, also helps strengthen bones. A medicine called menatetrenone is a vitamin K2 preparation that may be prescribed to strengthen bones in conditions such as osteoporosis.

So what happens if someone taking warfarin is prescribed a vitamin K2 medicine by an orthopedic surgeon to prevent fractures? In fact, warfarin’s blood-thinning effect drops so much that it can no longer be relied on. Even though the person is taking it, it can no longer be expected to prevent clots and keep blood vessels from becoming blocked.

Before every consultation, you are asked, “Are you being treated for any illnesses, or taking any medicines?” If you give accurate information about yourself, interactions like this can be prevented by checking in advance.

What is duplicate prescribing?

There is another reason why unnecessary medicines pile up. Let’s again use cardiology and orthopedics as an example.

Low-dose enteric-coated aspirin, often prescribed by cardiologists, thins the blood by suppressing a clotting mechanism in which platelets gather and clump together. However, it can burden the stomach and other parts of the digestive tract. If bleeding occurs in the stomach or elsewhere, it is hard to stop, and because it is painless, it may go unnoticed, so taking a stomach medicine alongside it is recommended.

Some painkillers often prescribed by orthopedic surgeons also irritate the stomach, so painkillers and stomach medicines may be prescribed as a set.

As a result, two departments each prescribe a stomach medicine, and the number of medicines increases. This is called duplicate prescribing. With stomach medicines, there is relatively little concern about side effects, but because the person ends up taking several similar medicines, the number of medicines they don’t really need goes up.

However, some stomach medicines work in different ways and sometimes do need to be taken together. Don’t stop any medicine on your own; whenever you feel uneasy, be sure to ask.

Feeling that you take too many medicines is a good reason for a review

People sometimes tell me, “I’ve been taking this medicine for decades.” But over the years the body itself changes, and how a medicine works may have changed too. A better medicine may also have become available.

When receiving medical care, it is important to give professionals accurate information. Using your medication handbook (okusuri techō, the booklet in which pharmacies in Japan record your prescriptions) is also a good safeguard.

Have a regular pharmacist

When you have questions or concerns about the medicines you take, consult a pharmacist, the expert on medicines. I also recommend having a “regular pharmacist” (kakaritsuke yakuzaishi).

Under Japan’s regular pharmacist system, one dedicated pharmacist is assigned to a patient and manages their medicines on an ongoing basis, keeping all their medication information together at one pharmacy. Not every pharmacist can take on this role; it is limited to pharmacists who meet certain conditions, such as at least three years’ experience at an insurance-covered pharmacy and a record of continuing training. The patient’s consent is required, and the out-of-pocket cost is slightly higher than usual (the amount depends on the patient’s insurance co-payment rate and revisions to medical fees).

When one pharmacist keeps track of all your prescription and over-the-counter medicines, they can check for duplication and interactions and also keep monitoring how well your medicines work and whether there are side effects, so you can take your medicines with peace of mind.

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About the author: 齋藤 直裕 (Pharmacist)

Graduated in pharmacy from Nihon University. Certified Sports Pharmacist. A home-visit pharmacist actively involved in home healthcare (as of the time of writing).

This article is a contribution from a medical or care professional, re-edited by our editorial team. It provides general information as of the time of writing, and symptoms and circumstances differ from person to person. For specific decisions, please consult your doctor, dentist, pharmacist or another professional.

This is an English translation of a column originally published in Japanese by Next Co., Ltd.

About Next Co., Ltd. We are a Tokyo-based company working in Japan’s senior care and end-of-life planning field. Alongside these expert columns, we publish professional training textbooks and support businesses entering Japan’s eldercare market. More expert columns | Our English textbook | Contact us