1. gift tax consideration
You lend your friend a interest-free loan. The loan itself is not a gift, but the uncharged annual interest is gift and subject to gift tax. However, let's say the market rate is 3%, the uncharged interest for $100K is only $3K, well within the gift tax exemption limit.
Conclusion: you do no need to report the annual interest gift.
2. Bad Debt Deduction
A cancellation of bad debt is a taxable income to the borrower. For the lender, you might be able to deduct bad debt from your tax. But it could get complicated on whether the "bad debt" is really a gift or debt. See following links, (at the risk of people calling me cut&paste google machine again).
Or google "non-business bad debt deduction".