Alison: Unfortunately most haircare products do contain preservatives. However, here are a few tips. If you have a dry, itchy scalp, try putting on a little of the Ojon Restorative Hair Treatment, massaging it into the scalp and leaving it overnight. It should help to moisturise the dry skin plaques on the scalp area, which may be causing the itchiness.
An even simpler trick, if your scalp is really flared up, is to drizzle on a little pure almond oil or even olive oil about five-ten minutes before washing. Just massage this into the driest areas and then shampoo. You may find that having moisturised the dry areas, your shampoo will be less irritating than before.
Plus you could also try the Philip Kingsley Scalp Mask.