It is legally permissible for both 401(k) plans and 403(b) plans to offer participant loans for any need that a participant may have - however there is no legal requirement that such plans must have a loan feature. In addition, if a plan does make participant loans available, different plans may have different "loan policies" that loan requests from participants must meet in order to qualify for a plan loan. Also, there are legal limits imposed by the law that apply to all participant loans.
If you desire a participant loan from a qualified retirement plan that you participate in, you should contact the Plan Administrator and ask for a copy of its "Loan Policy" and a Loan Application. Fill out the application and return it to the Plan Administrator for further processing. You will be notified of any additional requirements that may be necessary and you will also be notified if your loan request is granted and/or if your request needs to be modified.
If the plan(s) have a loan feature, the process should be easy.
Check with your tax advisor, as most Financial Advisors are not permitted to give tax advice.
Monies in qualified plans (401(k)s and 403(b)s are both qualified plans) are accessible without early distribution penalties for medical reasons. You may have to pay state and / or federal taxes.
This might be an alternative to taking a loan that would have to be repaid.
Again, check with a qualified tax professional.
First off, I want to say I hope that the bills are from a successful medical procedure and that everyone is doing well.
As mentioned there are some retirement plans that allow for you to take a loan from yourself and you can use that money to do whatever you would like to. Each plan has that has a loan has certain policies that you would need to meet to get the loan. Find out what those are. From the little information that you have shared, it would be nice to be able to lock your interest rate in at a lower rate, plus the interest that you pay on the loan goes into your retirement account. So, not only would you be paying a lower interest rate, but the interest that you are paying is going to yourself instead of to a CC company.
The other option that you have is a hardship distribution and it sounds like that since this is from medical bills it would qualify. If you were to take a hardship, and are younger than 59 1/2 you will be charged a 10% penalty for an early withdrawal plus the money, if it is not in a Roth account, will be added to your income for you to pay income taxes on. On top of that, you will be banned from making contributions to your plan for 6 months (probably something you do not want).
Those are the two options of accessing the money. Best of luck on the decisions ahead.