It is proven that the injection of lanthanum solutions produces glycohemia, low blood pressure, degeneration of the spleen and hepatic alterations, in the animals. The element is not absorbed orally, and when injected its elimination is very slow. The lanthanum compounds cause ocular irritations in the conjunctive and opacity of the cornea after a latency period of some hours. The exposition to lanthanum vapors induce irritation and refines the senses of the palate and of the smell.

Some rare-earths chlorides, such as lanthanum chloride (LaCl3), are known by its anticoagulant properties although they should be used with very care. Lanthanum salts are generally considered to have low or moderate toxicity.