When You Wonder, “Is This a Side Effect?”: Types of Side Effects and How to Notice Them Early

Written by: 齋藤 直裕 (Pharmacist)

Whenever you receive medicine, you are almost always told about side effects: “Please watch out for this.” The information leaflet lists side effects one after another as precautions, and reading it carefully can be frightening.

A side effect is an effect that is not intended or not wanted. In fact, every medicine has side effects. And it is precisely because side effects exist that the pharmacist’s profession exists.

1. Side effects from a medicine acting too strongly

Side effects can occur when a medicine works too well. For example, a medicine that lowers blood pressure may work so well that blood pressure drops too low.

This can happen simply because the dose was too high, because another medicine taken at the same time made the blood pressure medicine work too strongly, or because a food and the blood pressure medicine affected each other and amplified its effect.

Blood pressure medicine is taken to lower high blood pressure, easing the burden on organs rich in blood vessels such as the heart and kidneys and preventing serious illness. But if blood pressure drops too low, less blood reaches the brain, and the person may feel sluggish, become dizzy or faint.

In this case, knowing that the medicine lowers blood pressure, and what symptoms appear when it drops too far, will help you notice early.

2. Side effects that cause different symptoms

Some blood pressure medicines work by widening the blood vessels, which lowers the pressure on their inner walls.

Blood vessels are like tubes made of a muscle called smooth muscle, which stretches and contracts, and blood pressure also rises when vessels stiffen. These medicines lower blood pressure by relaxing this smooth muscle, but the intestines, for example, are also moved by smooth muscle, so their movement may relax too.

When the intestines move less, stools become harder to pass; in other words, constipation, an unintended and unwanted effect, may occur.

This side effect is more likely in people who are already prone to constipation, so it can be anticipated if you tell professionals about your constitution in advance. Remember that medicines act not just on one specific spot but on the whole body.

3. Allergic side effects

Because medicines are also chemical substances, the body may recognize a medicine as something foreign. If it doesn’t agree with you, an allergic reaction such as hives or difficulty breathing may occur.

Because it is an allergic reaction, it can occur not only with medicines but also with foods, health foods and over-the-counter medicines. It also occurs regardless of the dose, and with the same medicine, some people have no reaction while others have severe symptoms.

If, after starting a medicine, you feel “Hmm, something’s wrong; this isn’t normal for me,” stop taking it right away and seek advice.

4. Side effects that strain the liver or kidneys

Side effects range from ones so mild you don’t notice them at all to ones that are severe and distressing.

For example, some painkillers both suppress inflammation (fever, pain and swelling) and constrict blood vessels. When blood vessels constrict, less blood flows into the kidneys, which can impair kidney function.

When kidney function declines, urine output may fall, swelling may appear, appetite may drop and the person may feel sluggish. And because the kidneys make urine and remove unneeded substances from the body, when they work less well, substances that are bad for the body can build up.

Then the medicine itself is not excreted and stays in the body, which can set off a vicious circle in which its effects become too strong. Even people who have taken a medicine regularly for a long time may not easily notice this.

What matters is having regular checkups (including blood tests) and a regular pharmacist who knows what you are usually like and whom you can consult right away when something feels different.

Case: Persistent diarrhea caused by a stomach medicine

Here is something that happened.

A patient had been taking a stomach medicine twice a day, one tablet after breakfast and one after dinner, and switched to a once-a-day type “because taking it twice was a hassle.”

About a week later, the patient developed diarrhea and, thinking “Maybe it’s something I ate,” got by with antidiarrheal medicine. Because the patient had always been constipated and couldn’t pass stool without laxatives, they apparently thought, “My stomach feels nice and clear; this is just right.”

But the diarrhea returned whenever the antidiarrheal was stopped, and it went on for one month, then two, so the patient finally realized something was wrong and had tests at a hospital.

The tests found nothing abnormal, but when the doctor asked whether anything had changed and the patient thought back to when the diarrhea began, they arrived at the change of stomach medicine. When the patient went back to the original stomach medicine, the diarrhea stopped within three days and things returned to normal. The diarrhea is thought to have been a side effect of the new stomach medicine.

The side effect lasted a very long time, and the patient must have gone through a hard time. They said they never imagined it could be a side effect of a medicine.

If information such as “this medicine can cause diarrhea,” the patient’s usual tendency toward constipation, and changes after starting the new medicine had been shared in advance, there would have been a chance to notice the side effect and act much sooner. It was a case that made us reflect.

Side effects can be caught early

Each medicine has a track record built up from the experience of many people, and information on common side effects and the circumstances in which they occur is updated daily. In fact, pharmacists have a role in reporting such cases of side effects to the government, which accumulates the data and uses it to make drug treatment safer.

Telling professionals about your constitution and other details before you start a medicine can help prevent likely side effects or catch them early. Looking at the whole picture, including illnesses you are currently being treated for, eating habits and living environment, reveals which side effects are likely.

To face treatment with confidence rather than fear of side effects, it is important to know which side effects might occur and to check regularly for the ones most likely to appear.

---

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