In some cases, experimental drugs should be allowed for human consumption as long as the individuals are clearly aware of the risks of taking un-approved drugs. In some cases, people may be out of options, and if they are terminally ill, it's not as much of a risk. Plus, if they work, it will hopefully result in approval and use of new medicines.
Patients with cancer and other life-threatening diseases are often left with no treatment options except for drugs that are still in experimental stages. Taking these medications offers this group real hope. Also these drugs need to be tested on humans before they can be approved for widespread use. Allowing their consumption by patients who have no other options is a great way to prove their worth.
I believe if it is made known that an experimental drug is not yet approved then it should be the individual's choice whether or not they want to consume the drug for medical reasons. Many times a drug remains unapproved because of little evidence of its affects on humans and it should be the persons individual choice to weigh out the symptoms of their medical condition to the possible risks of the drug.
The FDA has procedures for experimental drugs for a reason. Many of these drugs prove to be dangerous. There are also fast track programs that allow people to get the drug approved faster. Another option is to enroll in an experimental trial. Some drugs end up hurting people more than they help.