Loans are permissible in Islam only if they are to be returned later in the same amount. It is lawful and strongly encouraged through numerous verses and hadiths as a way to help others and easing their problems. 

Loans: definition and supporting evidence

A loan is money given by one person to another to be returned later in the same amount, so as to benefit the recipient only. It is legitimate, as is clearly stated in numerous Qur’anic verses and hadiths that encourage helping others and easing their problems. It is universally agreed by Muslims that loans are perfectly lawful.

Abu Rafi' reports that ‘Allah’s messenger borrowed a young camel from a certain man. He subsequently received a number of camels which were part of people’s zakat. He ordered Abu Rafi' to give the man a similar camel. Abu Rafi' came back later and said that the youngest camel among them was already over six years old.