If Calcarea Phos (or any other biochemic salt) is the homeopathic simillimum and is prescribed as a biochemic salt in their low potencies, will it unnecessarily aggravate as the dose may be unnecessarily large when the remedy is the simillimum and the patient is extremely sensitive to the remedy on account of the similitude?
This is a very good question. You are talking about the habit of giving biochemic medicines in lower triturations frequently. The use of so-called biochemic medicines in such a blind fashion needs to be condemned. If someone says that Calcarea phos 6x is biochemic and Calcarea phos 6c is homeopathic, he/she is living in a fools world! A potentized medicine whether biochemic or homeopathic bears same rules for administration and repetition.
The keyword in your question is that the medicine is simillimum. When a medicine is simillimum to a persons state, the person is more sensitive to the action of that medicine. Therefore a relatively smaller stimulus is sufficient to bring about curative results. If Calcarea phos is the simillimum in a given case and it is repeated frequently as a biochemic salt, the chances of aggravation are very much there. If the medicine is similar, there will be a homeopathic aggravation. If the medicine is not similar, there will be a medicinal aggravation.
Another aspect of your question is that the medicine is given in low potencies. Look, selecting a similar medicine and selecting the right potency are two different things. If Calcarea phos is similar, the choice of potency will depend on numerous factors which I can not elaborate here. There is an article in the Philosophy section at Hpathy.com about potency selection. I would urge you to go through it. A person may respond well too Calcarea phos 6X and another person may need Calcarea phos 1M. Just like remedy selection, potency selection also needs individualization.