Generally, one column form is considered the best practice for form design. However, when the form has too many fields it wouldn't look good to create a super long form that spans 3+ screens either. For business/patient information, breaking down the form down into steps or collapsible parts are not great solutions as well. Shall I just use a multiple-column form instead?
That depends on what you mean by 'multiple column'. Multiple columns work especially well when the form inputs within a row are related. For example:
| First Name | Middle Name | Last Name | | Address | | City | State | Post Code | | Employer | Start Date | End Date |
You can see how this makes better use of the space, and gives a visual organization to each section of the form.
On the other hand, if you mixed and matched form inputs within a single row the form would be extremely confusing and my hunch is many would abandon.