Having itchy scalp can be unbelievably frustrating when:

You don’t know what’s causing your itchy scalp or dry flaking sometimes with redness and/or a scalp rash that drives you crazy
You have tried so many shampoos and treatments off the shelf but it keeps coming back and still your scalp is itching and sore.
You are constantly aware of the embarrassment of dandruff flakes falling on your clothes
You are worried about hair thinning and the long term effects of your itchy scalp condition on your hair and scalp
After all you have tried you still don’t know why you have itchy scalp in the first place and where it came from
Well then it will be no surprise to her that most of the scalp treatments that promise relief from dry scalp conditions only offer a temporary fix (if you are lucky). This is not an uncommon tale and there is reason for this.  Firstly these products aren’t focused on the cause – just the symptoms.  Herein lays the answer.  If you can understand the reason(s) why people end up with itchy scalp and the effects that a lot of common ingredients in shampoos are proven to have on skin that is already out of balance – then most of us would say "of course I have itchy scalp".
Sodium Laureth/Lauryl Sulphate (SLS)?  What’s that?  Why do you have to call a Poison Control Center if you accidentally swallow shampoo?  And what are those warning labels on the back all about?  What does it do to your head if it’s that toxic?
What you must know is that several chemicals, especially SLS, strip the natural oils from the skin and even corrode it, along with your eye membranes.  Have you also noticed that your hair has been thinning?  Well hair follicle damage is another little known but very common symptom of these chemicals.
Actually, most commercial shampoos & scalp treatments are designed to meet people’s "sensory" expectations…offering instant gratification and the illusion that they are doing their job.  Again therein lays the problem.  For example adding silicone to conditioner induces an artificial shine but in truth can create problems long term including sensitivities.
Most people expect a shampoo to:

Foam up nicely
Smell good
Take all the so-called "nasty" oiliness out of their hair
Make their hair feel squeaky-clean
And that’s a reasonable ask - think about it…if your shampoo didn’t foam up, smell good, or leave your hair feeling squeaky-clean, would you trust it?  Well, here’s the thing: 90).  Let’s look at sensitizers and allergies for a minute…
Sensitizers: Sensitivity is the result of a response by our immune system from being exposed to a substance or "foreign body" that it wants to keep out of the body. Sensitivity normally develops over several years (or months in children). The reason sensitizing chemicals often "slip under the radar" is because the first use of a sensitizer (e.g. from a synthetic colorant in hair dye) may not trigger a reaction, but subsequent or repeated use can cause a person to develop an allergic reaction to even very low levels of the original or related substance. A reaction can "hit you" seemingly suddenly, when really it is the result of a "build-up" of your immune system’s response over a period of time.
Irritants: Irritants on the other hand are quite different to sensitizers and allergens which involve the immune system. An irritant is a non-allergic inflammatory reaction at the site of where the substance was applied (yes sensitizers can cause rashes elsewhere on the body). The difference is that dermatitis (a non fungal dandruff) is commonly the result of irritation directly from a product, whereas allergens and sensitizers (especially the highly sensitizing products used in hair dyes and colorants and henna tattoos) will effect your immune system in a way that is difficult to "get at" because once you develop a sensitivity, it’s with you forever! Common hair dyes contain some of the most carcinogenic and sensitizing ingredients of all. If you have ever had a "fake tattoo" that is henna based, then beware – there have been many cases of severe allergic reactions to the compound PPD (phenylenediamine) requiring hospitalization in people who have applied a hair dye (black or dark brown in particular) after having had a henna tattoo.
So what non toxic itchy scalp treatments, shampoos and natural remedies can help?  Well as I stated above, there are many non toxic shampoos which are nourishing and conditioning while still giving you’re the "foam effect", they smell divine with the addition of the natural oils they contain.  So you do have a choice and it does NOT have to cost you more – in fact most of them are less – you just have to know what to look for.
Here are some of my favorite natural oils you can use for hair & scalp treatments that can be found in shampoos such as Akin.
Zinc Pyrithione: Wonderful stuff for dandruff & itchy scalp conditions.  First synthesized in the 1930’s, this is the most widely used active ingredient from a natural source.  It’s used to treat dandruff, seborrheic dermatitus, psoriasis, eczema and numerous other skin and scalp disorders.  It has strong anti-fungal and anti-bacterial properties. Zinc in a common ingredients in Scalpmeds treatments.
Jojoba: Is excellent as a scalp moisturizer and helps to rebalance sebum.
Tea Tree: Oily hair … Treatment for dry scalp, dandruff, lice, and under active sebaceous glands, enlivens the scalp and brings the cells & follicles to attention 
Basil: Oily hair … promotes growth
Chamomile: Fine to normal hair … gives golden highlights
Clary sage: All types of hair … dandruff treatment