The short answer is that there is no oral form of human growth hormone. Real growth hormone is a protein that would be broken down in the stomach, which is why the prescription version is given by injection and only for approved medical conditions.
Products sold as HGH supplements are usually blends of amino acids such as arginine, ornithine, glutamine, and lysine, sometimes with herbs or vitamins. The marketing claim is that these raise your own growth hormone. The research does not support that in any meaningful way. Studies of oral arginine, for example, found that it does not raise resting growth hormone and may even blunt the rise normally seen with exercise.
What genuinely influences growth hormone is deep sleep and intense exercise, both of which produce natural, short-lived increases. If you are considering one of these products, judge it on transparency and value rather than on growth-hormone claims, and talk to a doctor first.
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This page is general information, not medical advice. Real human growth hormone is a prescription medicine given by injection. Products sold as HGH supplements do not contain growth hormone. Talk to a doctor before starting any supplement, especially if you take medication or have a health condition.