Ought to be noticed just here, because it seems, at first sight, so much like Spigelia, and Hering says it follows Spigelia well in heart disease.
Both remedies have severe neuralgia of the face, but Kalmia is oftenest right-sided, Spigelia left. Both have pains in eyes, worse on turning them, but Kalmia has a sense of stiffness (Rhus tox. and Natrum mur.). Spigelia eyes hurt as if too large for the orbit. Both affect strongly the heart, and are useful in heart troubles of rheumatic origin. Both have violent, visible, tumultuous action of heart; Spigelia is invariably so, while Kalmia has at times remarkable slowness of the pulse (like Digitalis). The Kalmia form of rheumatism, like Cactus, goes from above downward (Ledum from below upward), and the pains in Kalmia shift suddenly. If we were called to a case of migratory rheumatism, and the heart seemed to be suffering, we would think of Kalmia before Pulsatilla, of course all the other symptoms taken into consideration. The pain of Kalmia often extends down to left hand (Rhus).
So far as the neuralgic symptoms of Kalmia are concerned, they are not much like Spigelia, except that they locate in the face, and are very violent. The sides and time of aggravation are different, and Kalmia is not often found involving the whole head, like Spigelia. Hering mentions that with Kalmia "weakness is the only general symptom with neuralgia" The neuralgic pains of Kalmia are sometimes attended with, or followed by, numbness of de parts affected, in this resembling Aconite, Chamomilla, Gnaphalium and Platina. It is to study up the points of resemblance of remedies having a particular affinity for the same region or organ, and to note ado more particularly the differences, that perfects the true homopathic prescriber. No kind of labour will bring better returns.
Maharana Homoeo Reader