Avoid abbreviations whenever possible. Do not use the abbreviation if it only appears once, unless it's more commonly used than the full term (see below for examples).
Define each abbreviation the first time you use it in a section. For example, disease-modifying antirheumatic drugs (DMARDs). Define immunoglobulins such as IgA, IgD on first mention as well because screenreaders read the abbreviation out as a word.
Do not use full stops in abbreviations (US, NHS), contractions (Ms, Dr) or initials (Dr HJ Baker).
Many common abbreviations are better known than what they stand for, so they do not need to be defined (in fact, to define them may make things less clear!).
Do not define:
This list is not exhaustive. Use common sense and think about what the user is likely to be familiar with.
Use the US to refer to the country, not America or the USA.
Do not use NICE-specific abbreviations (use technology appraisal, guideline committee, appraisal consultation document; not TA, GC, ACD).
Do not use e.g., i.e. or etc. Use for example, such as, that is and so on.