How much experience you include in your CV will depend on many different factors including how many different career paths you’ve had, how long you’ve been in your current position, and how relevant your previous experience is to the types of roles you’re now applying for.
Most recruiters agree that including between 10-15 years of experience on your CV is best, especially if they can see your growth from where you started out to where you are now. Even if you’ve been in the pharma industry for longer than this, this amount of time should still show employers how you’ve developed, as it’s unlikely you’ll have been in the same position for this length of time. Also, the pharma industry won’t look the same now as it did 15 years ago, so although you can still talk about previous experience beyond this, it won’t be as relevant to employers as what you’ve achieved recently, and how this ties in with where the industry is now headed.
However, if you’ve had 10 different jobs in the last 10 years, be mindful of the fact that your CV shouldn’t be longer than 2 or 3 pages, so you may want to limit the amount of information you include under some of the less relevant headings, perhaps only including the job title, the length of time you worked there and your biggest achievement. Highlight your most impressive achievements in the most relevant roles, and if recruiters want to find out more about some of the other positions you’ve listed, then this is something they can ask you about in the next stage.
Whether you’ve listed 5 years of experience on your CV or 20, remember that if it’s on there, then you should be prepared to talk about it and answer questions about your responsibilities and the impact you had in each role.