Neither can you be given treatment without consent if you are under a guardianship order or subject to supervised discharge. In these instances if it were decided that you needed treatment, then common law powers would have to be used. No matter what your circumstances, your consent should always be sought. The Power to give you treatment under the Mental Health Act only covers treatment for mental disorder. Not for physical ailments unless they give rise to a mental disorder or are inherently connected with it.
Some medications require blood tests to be carried out.
It is generally agreed that these are an integral part of a treatment and can be done without consent. It has also been agreed that if you suffer from anorexia then being given nourishment is a valid treatment. If you are being given treatment without your consent then this can only be done for 3 months. If it is to carry on after this then a second opinion from a specially appointed doctor has to be obtained. There are also 2 categories of treatment which are considered particularly hazardous and which have special criteria.