Derfen has no side effect. If you apply too much lotion,the skin of your horse can become a little bit more sensitive and warm. You should then suspend applications until the skin gets back to its original state.

When temperatures go really high with no wind, the smell of Derfen applied may incommode the horse because it has a keen sense of smell. If so, the horse will lower its neck and appear tired for a few minutes. There is no danger at all for the horse but you want to keep it away from the sun when you apply Derfen.

Some horses are more sensitive than others and feel irritated when Derfen is applied. Itching will increase temporarily as the horse actually wants to stop the irritation. If such happens, mix Derfen with petroleum jelly (vaseline) or with shea butter (avoid any other greasy element that could ract when placed in the sun)