I would really like to have your input on this! Firstly, are there any???? Except in some few?

Actually we can have adverse reactions, which are side effects, to just about anything.  Even oxygen is regulated as a drug since it can cause side effects.  And look at how many foods can cause side effects such as allergies.

Herbs are no different.  But certain herbs have a higher risk of certain side effects.  I have been working on a list of herbs to avoid or use with caution due to their high risk of side effects.  

For example the berberine herbs (goldenseal, barberry, Oregon grape root, coptis; also known as goldthread) since these kill the intestinal flora, can damage the intestinal lining, and lead to potassium loss and increased blood pressure.  

Another example are the high anthraquinone containing herbs (senna, cascara sagrada, rhubarb root and Cape aloe.  These are harsh stimulant laxatives and weaken the intestinal muscles after as little as two weeks use.

Some herbs have to be aged to render the safe enough for use at all.  Cascara sagrada for example has to be aged at least two years before it can be used without causing extremely severe intestinal cramping.  Pyrrolizidine alkaloid (PA) herbs (comfrey, germander, coltsfoot and chaparral all need to be dried and aged at least 2 months to oxidize the PAs preventing liver damage.  Horsetail grass (shavegrass) has to be dried to destroy the thiaminase enzyme.

If there are certain conditions already present then particular herbs can be contradicted.  For example cayenne is not recommended in cases of bleeding ulcers or salicylate sensitivities.  

Yucca root is also contradicted in cases of bleeding ulcers since the saponins can hemolyze red blood cells.  

Echinacea and aloe are not recommended in cases of autoimmunity since these increase white blood cell activity.  

Juniper berry, Devil's club and bitter melon are contradicted in cases of hypoglycemia since these all severely drop blood sugar.  

Horsetail grass (shavegrass) is contradicted in cases of heart failure, arteriosclerosis, diabetes or Raynaud's disease or phenomena since horsetail's nicotine content further constricts blood vessels.

And what can be a benefit to one person can be a side effect for someone else.  European mistletoe for example lowers blood pressure, which is good for a person with hypertension, but not hypotension.  American mistletoe on the other hand raises blood pressure, which can be good for hypotension, but not hypertension.

And sometimes "side effects" are not really side effects.  For example, poke root contains a substance called poke activating factor (PAF).  PAF is structurally similar to interferon and has the same effects.  So it can cause symptoms such as fever just like interferon.  But this is not a side effect, it is activation of the immune system.  Poke can still be toxic if used improperly though and should only be used with guidance or by those really familiar with the herb.

Some herbs are just too dangerous to use without really knowing what you are doing.  Some examples are the cardiac glycoside herbs (foxglove, oleander, squill, etc.).  Other herbs best avoided due to toxicity include pennyroyal, false hellbore, blue cohosh and daturas.

Would you rather talk in terms of contraindications than side efects?

Contraindications are also an issue that has to be addressed.

Many herbs contain blood thinning coumarins that can interact with Coumadin (Warfarin) increasing the blood thinning effects.  Examples are dong quai, sweet clover and lomatium. 

Salicylate herbs such as cayenne, birch and wintergreen can also thin the blood and interact with blood thinners.

Not all the interactions are between herbs and medications.  Ginger should not be taken with lobelia since it can theoretically stop breathing if too much lobelia is taken.  

And not necessarily a danger, but taking juniper berry with uva ursi can interfere with the uva ursi from doing its job. 

High tannin herbs such as uva ursi, white oak bark, red raspberry leaf and green tea can block the effects of other herbs they are combined with.

Keep  in mind that this is just a partial list of possible issues.  This is why it is so important to learn about the chemistry of herbs, how they work, interact with drugs and each other, how they affect things such as the flora and other immune factors, etc.