Worming:
Many people ask about worming, there are several different products out there they are either herbal, which you can eat their eggs after you have wormed your hens, or non-herbal. When worming your hens with the non-herbal wormers you can't eat there eggs up to three weeks. You should try and worm your hens every 6 months.
Colds:
More than likely your hens will pick up a cold from other birds that have been on your garden. Not to worry you can give them something to help them with their cold, citricidal. Citricidal is a grapefruit seed extract which has natural antibiotic properties which will help your hens to overcome most illnesses, and is available at most health shops.
Red mite:
As mentioned red mite is a blood sucking parasite which feeds on your hens at night, this does sound quite nasty, but there are several treatments. The treatments come in several different forms: powers, sprays, and aerosol sprays. They are all equally as good, but if you have a serious red mite infestation you can use creosote and this will kill off all the red mite. If you do use creosote you will have to temporally house your hens else where for a week or two.
Vets:
If you are unsure about what to do with your hens you could always consult a vet, but make sure your local vet is knowledgeable regarding poultry as many vets may only know the basics or even worse nothing.