Sweet Itch is like our Queensland itch and I have had success with treating this. It helps the progress if you are able to protect from the biting insects.

Use this in conjunction with covering the horse and if the horse is not one of the few that develop severe allergic reactions to the bites, it is successful.

I have had horses though that still suffer seasonally quite badly and really the only recommendation for them is to remove them from that area.

My first approach for the Sweet Itch is to give blood cleansers.

The mix will need to be run for a full Blood Cycle of 12 weeks (which would be 2 bottles).

At about the 5 week mark you may notice a slight increase in the itch which is very normal as the herbs detoxify the system.

I also recommend keeping the horse lightly covered with a cotton rug and hood if possible.

Also have a good read of the following article on Queensland Itch:

Giving your horse Chamomile every day and adding fresh garlic, molasses and rosehips tea to the diet will also support the improvement in immunity and toxin removal.

Chamomile tea made with flowers;
Dose rate is 4 dessertspoons made into a tea with 1 litre of boiling water and given with feed.

Rosehip tea made with granules;
Dose rate is 2 dessertspoons made into a tea with 1 litre of boiling water and given with feed.

You can mix the teas into the same 1 litre of water.

Molasses and Garlic recipe;
I recommend that you soak 1 kilo of unpeeled garlic cloves ( just roll the corns underfoot slightly) into a 5 litre tub of molasses, allow to steep for 3 weeks then it's ready to use. Dose half a cup daily including cloves.