4. MeSH will probably NOT help you if:

Your topic is a new or emerging medical concept for which a MeSH term may not yet exist.

You suspect that very little has been published on your topic - meaning, again, there is probably no MeSH term.

You want to retrieve recently published articles. There is a short lag time (a few days to a few weeks) between when citations enter the PubMed database and are described with MeSH terms.

Keywords are the only way to retrieve articles in the situations described above.