Why all medicines have side effects?

[ikos9lives]

Responses from physicians, scientists, or PF members sought and welcomed.

 

[Upisoft]

Responses from physicians, scientists, or PF members sought and welcomed.

Everything has side effects, not only medicines. Even the oxygen you breathe.

 

[Andy Resnick]

Responses from physicians, scientists, or PF members sought and welcomed.

Sometimes the side effect is the desired effect: Rogaine and Viagra are two examples.

 

[jaseh86]

Fundamentally, most drugs aim to affect processes in a particular part of the body that may be functioning abnormally. In most cases, the targeted process often exists in many other parts of the body and so the drug will affect all areas, even in the non-target areas.

Furthermore, all drugs are chemical compounds and too much of these can be damaging to our cells, which lead to generalised side effects as a result of tissue damage in certain regions.

For example, NSAIDs such as aspirin are used for preventing blood clots because they inhibit a certain group of enzymes in platelets. However, these enzymes are also present in the stomach lining and serve to protect the lining. Aspirin unfortunately cannot distinguish between them and so while it prevents clots, it also prevents the protection of the stomach lining which leads to ulceration.

I would say most side effects are caused by a similar mechanism simply due to the non-selective nature of all drugs. There are drugs that are getting more and more targeted but even these still affect unwanted parts of the body.

 

[Siv]

Medicines have side effects because there are no miracles. Human ailments don't have a panacea, a substance which only cures the ailment or was made to cure that ailment.
We have to find one that is the best trade-off. Sometimes there aren't any. Sometimes the trade-off is pretty good, and sometimes its not.

 

[mugaliens]

Everything has side effects, not only medicines. Even the oxygen you breathe.

This is an excellent example, and something which most people forget, namely, that life evolved here on Earth while our world was yet largely starved for oxygen. Early life produced oxygen, which at the time was a poisen to them. They evolved, as did the oxygen-users.

Laughter may be the best medicine, but good, clean living i.e. regular exercise, a healthy (not hardy) well-rounded diet and plenty of water does wonders for one's health! Sadly, our medical system still focuses on treatments of symptoms, often through the use of medications, rather than focusing on the cure (get thee off thy couch!), with the limited exceptions being those things which are a little more deadly, such as systemic bacterial infections, cancers, and non-curable, but easily treated hormonal imabalances such as Grave's.

 

[Ygggdrasil]

From a chemists' point of view, designing a good medicine is difficult because you need to design a drug that binds to and activates/inactivates one single type of target in a cell without binding to and affecting any of the other millions of molecules in the body (not to mention, making the molecule stable [but not too stable], able to cross biological barriers, easily synthesized, etc).

A good example here are antihistamines used as allergy medications. Allergies occur when allergens trigger histamine release by the immune system. Histamine is a small molecule that is detected by sensors on the surface of the celll called histamine receptors. When histamine binds to the histamine receptors, the histamine receptors tell the cell to trigger an immune response leading to the characteristic symptoms of runny nose, itchy eyes, etc.

Therefore, if we want to design an allergy medicine to prevent the symptoms of an allergy, we could try to develop antihistamines, molecules that inhibit histamine receptors, for example, by preventing histamine from binding to the receptor. The problem here, however, is that there are histamine receptors in cells throughout the body and these receptors are involved in many other functions. For example, histamine acts as a neurotransmitter in the brain and a class of histamine receptors in the brain help to regulate sleep and wakefulness. As these histamine receptors also bind to histamine, they are structurally very similar to the histamine receptors that regulate immune responses. Many of the features that would allow a drug to bind and inhibit one class of histamine receptor would be present in the other class. Thus, many early antihistamines could not distinguish between these two classes of histamine receptors and would inhibit both those that regulate immune responses and those that regulate wakefulness. Therefore, a side effect of many early allergy medications was drowsiness.

Luckily, there are very subtle differences in the structures of the two classes of histamine receptors. Chemists were later able to develop new antihistamines that bind to only the histamine receptors that regulate allergic responses and not those that regulate sleep. These new antihistamines allowed for the creation of non-drowsy allergy medicines.

The case is even worse for drugs like cancer drugs. Many cancer drugs target enzymes required for cancer growth. However, identical enzymes (not just similar enzymes) are present in other tissues, for example bone marrow and hair follicles, and are also targeted by the anti-cancer drugs. Avoiding side effects with these types of drugs would require finding drug targets present only in cancer cells but not in normal cells, a task which has proven extremely difficult in most cases.

 

[lisab]

Keep in mind, not everyone who takes a medicine will experience side effects. Many meds come with documentation in the package which shows the result of double blind studies. That documentation will give you a rough idea of what the chance is of getting a side effect.

Here's an example from one of the non-drowsy antihistamines Ygggdrasil mentioned:

In this case it looks like almost 90% of people who took that med reported no headaches, and ~97% reported no back pain.

 

[darkspace]

Let ask another question, what thing that is called side effect?
Whatever you eat, drink and inhale can react with your body. Because your body is alive chemical laboratory. That includes the natural things and industrial things. Your body job is to break anyting is taken down and use the advantage of them and excrete the bad or not used residues out of it, why? to not be under reaction with your body. When you take anything as you are waiting for certain effect or result; but when you experience additional effect or result, you can call it a side effect or undesirable results.
For example:
Some certain fruits make to some certain people allergic reactions. These allergic reactions can be called side effects.
Recent scientific studies proven that not all drugs can induce side effects to all the populations; but to certian group of population and that as a result of their genetic base which make a specific unique target to that drug.
If you had taken any drug according to its specifications, you would not have been experienced any side effect UNLESS you are susceptible to that drug due to certain cause like your genetic base, which maybe produce a unique enzyme or protein reacts with this drug to induce that certain side effect. In this case, you should not use that drug again.
As mentioned above NOT all side effects are BAD!
Like:
sildenafil (Viagra): it had been a drug for hypertension and today it is for erectile dysfunction.
Minoxidil: it had been a drug for hypertension and today it is for non-genetic alopecia.

I hope that was helpful,
Thanks

 

[phinds]

We have to find one that is the best trade-off. Sometimes there aren't any. Sometimes the trade-off is pretty good, and sometimes its not.

Boy, do you have that right. Some years back, I was working at Medco, a pharmaceutical distribution company, and saw in their daily newsletter that they were now distributing a new drug and one of the side effects listed was death.

I was shocked and went to a knowledgeable person there and asked about that statement, and she said "well, sometimes drugs that are the only known way to cure or mitigate a particular problem cause undesirable effects in addition to the good ones, and in rare occasions, that can include death. You don't think the drug is DESIGNED to cause death do you?.

So of course I said no and she said "see ... it's a side effect".

 

[Nik_2213]

Another problem is our genetic diversity. In addition, our bacterial gut flora will have a significant effect on meds. Also, our immune systems vary depending on our personal micro-history of exposure. Even sibs may react differently. So, side-effects may range from nothing to anaphylactic shock...

D'uh, then there's the psychosomatic factor: Even 'harmless' placebos may evince side-effects...