There are several ways in which you can go about paying for your expenses while going through an internship.
If you are lucky enough to get one of those internships where the interns are given some sort of allowance, then you can use the allowance to pay for your day to day expenses. Some organizations are so generous with their interns that they pay them (almost) full salaries. In some organizations, as an intern, you are actually entitled to a paycheck, which you (like all the other employees) may be able to access online on a site like Securitasepay.com. Under this arrangement you (as an intern) are given a Securitasepay login page, enabling you to be logging in and access your pay stubs, just like all other employees. If you happen to chance upon such an internship, you are unlikely to have difficulties paying for your day to day expenses.
If you are on an unpaid internship, you may have to use money from your student loan to finance your day to day expenses while going through the internship. You should have no qualms doing this, because in the final analysis, the internship too is a part of your education. To digress a bit, the whole concept of unpaid internships is a disturbing one. But more and more people are being forced by circumstances to go on such unpaid internships. It is nonetheless very unfair, especially when you also consider the role played by the interns – like, for instance, the role played by interns in a law firm. In the final analysis though, it is better to go for an unpaid internship and gain some experience and exposure, as opposed to not going through an internship at all.
At yet another level, if your parents are in a reasonably good position financially, you have the option of asking them to help you with the money you need to finance your day to day expenses while going through the internship. In that case, you’d need to point out to them the fact that the internship is an integral part of your education too.