Preventative medicines are medicines that are taken to prevent an illness rather than to treat it. Typical examples are vaccines, cholesterol-lowering medicines and blood pressure medicines.

How they work

Preventative medicines work in several ways. Some are designed to stop you developing a particular illness in the first place. For example, the influenza vaccine is designed to stop you getting the ‘flu’.

Some are designed to prevent you getting a recurrence of your condition, or prevent your condition getting worse. For example, certain asthma medicines (‘preventers’) are designed to reduce the number and severity of your asthma attacks.

Others are designed to prevent you developing the potential complications of your condition. For example, if you have high blood pressure, blood pressure tablets may be used to reduce your likelihood of having a heart attack or stroke, because having high blood pressure predisposes you to these conditions.

Preventative medicines don’t guarantee that you won’t develop the condition. Rather, they reduce your likelihood of developing it.

Deciding to use

Obviously, maintaining a healthy and active lifestyle is the best way to stay well and prevent illness. However, there are situations when a healthy and active lifestyle is not enough. In these situations, some medicines may play an important role in preventing illness.

Preventative medicines are prescribed only after weighing up the likelihood and consequences of developing the condition against the risks of taking the medicine. If the medicine is being used to prevent a recurrence or worsening of the condition, this decision is often more clear-cut than if the medicine is being used to prevent a condition developing in the first place.

For example, aspirin is often used to prevent heart attacks, because it makes the blood less sticky. However, making the blood less sticky also makes us more likely to develop bleeding.

People who’ve already had a heart attack have a greater likelihood of having another attack than people who haven’t had one. Using aspirin to prevent further heart attacks in these people is often easily justified, because the likelihood and consequences of having another heart attack clearly outweigh the possibility of developing bleeding due to aspirin.

However, the equation may be very different for people who’ve never had a heart attack, because the medicine will probably need to be taken long term for a condition they may never even develop. Therefore, the risks of using aspirin take on a greater significance. In determining the likelihood of developing a heart attack, the doctor looks at the person’s risk factors. Risk factors are characteristics that make you more likely to have a heart attack. The box below lists some of the risk factors for heart attacks. If you have only one or two risk factors, a preventative medicine may not be justified. However, if you have several or many risk factors, a preventative medicine is more likely to be justified.

Maintaining a healthy and active lifestyle is the best wasy to stay well and prevent illness.

In deciding whether to use a preventative medicine, you and your doctor need to consider the following questions.

• What is my likelihood of developing the condition?
• What sort of people does the condition usually affect, ie what gender, age group, etc?
• Do I have a family history of the condition?
• Do I have other conditions that predispose me to the condition?

The answers to these questions will indicate how many risk factors you have. You also need to consider…

• What is likely to happen if I develop the condition?
• How serious or disabling is the condition?
• What else could I do to help prevent the condition?
• What are the likely benefits and risks of using the medication?
• How long will I need to take the medication?

The answers to these questions will help you and your doctor decide whether the likelihood and consequences of developing the condition outweigh the risks of taking the medicine.

Take regularly

Taking any medicine requires persistence. When you take a treatment medicine, you usually notice its effects quite quickly, so you’re motivated to continue taking it as long as you feel it’s doing you good.

In contrast, some preventative medicines, such as medicines to prevent asthma (preventers), don’t make you feel any different. In addition, their effects may only be felt months or years down the track. Their lack of obvious effects can make it difficult for you to find the motivation to continue taking them regularly.

It’s important to overcome these thoughts when taking preventative medicines, because most of them must be taken regularly if they are to be effective. This may necessitate taking the medicine for many months or years, or even for the rest of your life.

If you’re having doubts about whether it’s worthwhile continuing to take your preventative medicine, talk to your doctor about your doubts, rather than just stopping it. They will understand that it’s not easy to keep taking a medicine for long periods, especially if it has unpleasant side effects, or seems like an unnecessary cost. They will be able to reconsider your need for the medicine, and go over the pros and cons with you again.

And, last but not least, don’t forget that preventative medicines are on top of rather than a replacement for an active and healthy lifestyle. Find out as much as possible about what you can do to reduce your likelihood of developing the condition or minimise its progression — and do it!