Life-Changing Medicines. Redefining Possibilities. Forward-Looking Statements “Safe Harbor” Statement
Under The Private Securities Litigation Reform Act of 1995 This communication contain forward-looking statements, including, but not limited to, statements related to Jazz Pharmaceuticals’ future financial and operating results, 2021 financial
guidance, growth prospects, 2021 and future goals, objectives and milestones, revenue diversification and the anticipated timing thereof; statements related to the proposed acquisition of GW Pharmaceuticals and the anticipated timing, results and
benefits thereof; potential expansion of the company’s pipeline; planned, ongoing and future clinical trials, including expected initiation of studies for JZP-385, Zepzelca and JZP-150, and presentations of data; geographic expansion activities, including potential approval of Sunosi in Canada; other product development and regulatory activities, including potential U.S. regulatory
approval of JZP-458 for ALL/LBL and JZP-258 for idiopathic hypersomnia; ongoing and potential future product launches, including Sunosi, Zepzelca, Xywav, JZP-458 for ALL/LBL and JZP-258 for idiopathic hypersomnia, and expectations regarding timing and achievement of payer coverage; the company’s expectations regarding
timing, availability and inter-quarter variability of Erwinaze net product sales; the timing of the foregoing events and activities; and other statements that are not historical facts. These forward-looking statements are based on the company’s
current plans, objectives, estimates, expectations and intentions and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements
as a result of these risks and uncertainties, which include, without limitation, risks and uncertainties associated with: Jazz Pharmaceuticals’ and GW Pharmaceuticals’ ability to complete the acquisition on the proposed terms or on the
anticipated timeline, or at all, including risks and uncertainties related to securing the necessary regulatory and shareholder approvals, the sanction of the High Court of Justice of England and Wales and satisfaction of other closing conditions to
consummate the acquisition; the occurrence of any event, change or other circumstance that could give rise to the termination of the definitive transaction agreement relating to the proposed transaction; risks related to diverting the attention of
GW Pharmaceuticals and Jazz Pharmaceuticals management from ongoing business operations; failure to realize the expected benefits of the acquisition; significant transaction costs and/or unknown or inestimable liabilities; the risk of litigation in
connection with the proposed transaction, including resulting expense or delay; the risk that GW Pharmaceuticals’ business will not be integrated successfully or that such integration may be more difficult, time-consuming or costly than
expected; Jazz Pharmaceuticals’ ability to obtain the expected financing to consummate the acquisition; risks related to future opportunities and plans for the combined company, including the uncertainty of expected future regulatory filings,
financial performance and results of the combined company following completion of the acquisition; GW Pharmaceuticals’ dependence on the successful commercialization of Epidiolex/Epidyolex and the uncertain market potential of Epidiolex;
pharmaceutical product development and the uncertainty of clinical success; the regulatory approval process, including the risks that GW Pharmaceuticals may be unable to submit anticipated regulatory filings on the timeframe anticipated, or at all,
or that GW Pharmaceuticals may be unable to obtain regulatory approvals of any of its product candidates, including nabiximols and Epidiolex for additional indications, in a timely manner or at all; disruption from the proposed acquisition of GW
Pharmaceuticals, making it more difficult to conduct business as usual or maintain relationships with customers, employees or suppliers; effects relating to the announcement of the acquisition or any further announcements or the consummation of the
acquisition on the market price of Jazz Pharmaceuticals’ ordinary shares; the possibility that, if Jazz Pharmaceuticals does not achieve the perceived benefits of the acquisition as rapidly or to the extent anticipated by financial analysts or
investors, the market price of Jazz Pharmaceuticals’ ordinary shares could decline; regulatory initiatives and changes in tax laws; market volatility; the ultimate duration and severity of the COVID-19
pandemic and resulting global economic, financial and healthcare system disruptions and the current and potential future negative impacts to the company’s business operations and financial results; maintaining or increasing sales of and revenue
from the company’s oxybate products and other key marketed products; effectively launching and commercializing the company’s other products and product candidates; the time-consuming and uncertain regulatory approval process, including the
risk that the company’s planned regulatory submissions may not be submitted, accepted or approved by applicable regulatory authorities in a timely manner or at all; the costly and time-consuming pharmaceutical product development process and
the uncertainty of clinical success, including risks related to failure or delays in successfully initiating or completing clinical trials and assessing patients such as those being experienced, and expected to continue to be experienced, by the
company as a result of the effects of the COVID-19 pandemic; protecting and enhancing the company’s intellectual property rights; delays or problems in the supply or manufacture of the company’s
products and product candidates; complying with applicable U.S. and non-U.S. regulatory requirements; government investigations, legal proceedings and other actions; (continued on next page) 2 February
2021