Here is a short note on the use of Gelatin in food and other products of use:
Gelatin is a protein made from animal products.It is produced by partial hydrolysis of collagen extracted from the skin, bones, and connective tissues of animals such as domesticated cattle, chicken, pigs, and fish.Chemically and medically, gelatin is totally a different product than its source collagen, and has totally different properties.
Those products that are forbidden by Islamic law, does not retain their applicability when the basic characteristics by which the product is identified are changed.The knowledge that have come to the ulema through professionals in the particular field, they have come to the conclusion, that Gelatin does not retain the true characteristic of the collagen of its source and so there is margin for its use.However due to the differences in the specialist in this field, some ulema have labelled it a better option to avoid Gelatin from sources which are haram(forbidden), such as pig.
Keeping in mind the difference of Islamic Jurists on this issue, ulema have requested Muslim industrialists to make their products from completely halal products so there is no shadow of doubt in it.
Source: Islamic Fiqh Academy India
In the end I would quote a hadith:
On the authority of Abu Abdullah al-Nu’maan ibn Basheer (may Allah be pleased with them both) who said: I heard the Messenger of Allah (peace be upon him) say, ‘That which is lawful is clear, and that which is unlawful is clear, and between the two of them are doubtful [or ambiguous] matters about which not many people are knowledgeable. Thus, he who avoids these doubtful matters certainly clears himself in regard to his religion and honour. But he who falls into the doubtful matters falls into that which is unlawful, like a shepherd who pastures around a sanctuary, all but grazing therein. Verily every king has a sanctuary and Allah’s sanctuary is His prohibitions. In the body there is a morsel of flesh which, if it be sound, all of the body is sound and which, if it be diseased, all of the body is diseased. This part of the body is the heart.” (Recorded in Bukhari and Muslim).