The Internet has changed the way we live, work and shop. The growth of the Internet has made it possible to compare prices and buy products without ever leaving home. But when it comes to buying medicine online, it is important to be very careful. Some websites sell medicine that may not be safe to use and could put your health at risk.

Millions of consumers are using the Internet to get health information. And thousands of web sites are offering health information. Some of those sites are reliable and up-to-date; some are not. How can you tell the good from the bad?

First, it's important to carefully consider the source of information and then to discuss the information you find with your health care professional. These questions and answers can help you determine whether the health information you find on the Internet or receive by e-mail from a Web site is likely to be reliable.

There are more opportunities today than ever before to learn about your health and to take better care of yourself. It is also more important than ever to know about the medicines you take.

If you take several different medicines, see more than one doctor, or have certain health conditions, you and your doctors need to be aware of all the medicines you take. Doing so will help you to avoid potential problems such as drug interactions.

Mixing two drugs together could make one of the drugs ineffective. The combination also could increase a drug's effect, and be harmful. The result might be mild symptoms such as nausea, stomach upset, or headache, or more serious symptoms such as a dramatic drop in blood pressure, irregular heart beat, or damage to the liver-the primary way that drugs pass through the human body.

When a drug is taken orally, it usually travels from the stomach to the liver, where it can be metabolized-the process of breaking down and removing chemicals from the body. Enzymes are complex proteins that act as catalysts in starting or speeding up chemical reactions. They cause a specific chemical change in other substances without being changed themselves.

It used to be that the only way to test for drug interactions was in people. Now drug companies can take five test tubes with the five major pathways for metabolism and put their drugs in to see whether it's metabolized by CYP450. This allows to generate a list of possible interactions based on their findings.

This phase of research in test tubes, known as in vitro studies, allows researchers to perform drug-interaction studies in labs by testing a drug with other drugs that have the same route. This has made the research faster and more accurate. If two drugs go through the same enzyme, the presence of one drug can prevent the metabolism of the other. So this allows you to look at the worst-case scenarios and ask: 'What if we put this drug with that one, knowing that they have the same route?'"

Not everything that happens in a test tube will become meaningful in humans, though. Results from these test-tube studies can tell us whether need to do further testing in people to find out if an interaction is clinically significant.

Researchers say there are several important variables that affect individual differences in how drugs are metabolized, including race, gender, age, and health conditions. For example, people with kidney or liver disease don't eliminate drugs from their system as well as people who are healthy. Very young children and older people have slower drug metabolism than others, and women may metabolize drugs differently than men in some cases.

In addition to having a good grasp of drugs and their effects, doctors take medication histories, and they consult with other members of their team to guide them in making decisions about drug interactions. They also use concise drug summaries and resources on pharmacological principles.

But it is good way -- consumers remind doctors of everything they take when they are prescribed a new medication. So a patient might say: "Now remember, I'm also taking birth control pills. Is there a risk of interaction with this new medicine?"

Some antibiotics, such as rifampin, can lower the effectiveness of birth control pills. Sildenafil, the active ingredient in the erectile dysfunction drug Viagra, should not be taken with nitrates for heart treatment because of the potential for dangerously low blood pressure.

Examples of food with tyramine are cheese and soy sauce. Grapefruit juice should not be taken with certain blood pressure-lowering drugs or cyclosporine for the prevention of organ transplant rejection. Alcohol should not be taken with pain relievers such as Tylenol (acetaminophen) or ibuprofen because of the increased risk of liver damage or stomach bleeding.

Although medicines can make you feel better and help you get well, it's important to know that all medicines, both prescription and over-the-counter, have risks as well as benefits.

There are several types of risks from medicine use: a) The possibility of a harmful interaction between the medicine and a food, beverage, dietary supplement (including vitamins and herbals), or another medicine. Combinations of any of these products could increase the chance that there may be interactions. b) The chance that the medicine may not work as expected. c) The possibility that the medicine may cause additional problems.

To obtain the benefits of riding in a car, you think through the risks. You consider the condition of your car and the road, for instance, before deciding to make that trip to the store.

The same is true before using any medicine. Every choice to take a medicine involves thinking through the helpful effects as well as the possible unwanted effects.

In many situations, the expert advice of your doctor, pharmacist, or other health care professionals can help you make the decision.

Important: think it through and work together with your doctor, pharmacist, or other health care professional to better manage the benefits and risks of your medicines.

Before use a medicine make sure you understand the directions; ask your doctor if you have questions or concerns. Always double check that you have the right medicine.

Read and follow the directions on the label and the directions from your doctor, pharmacist, or other health care professional. If you stop the medicine or want to use the medicine differently than directed, consult with your health care professional.

Before starting any new medicine or dietary supplement (including vitamins or herbal supplements), ask your doctor again if there are possible interactions with what you are currently using.

Tired routine? Getting know something new!