<p>Diphenhydramine is widely distributed throughout the body, including the CNS <sup class="text-reference-group"><a class="reference-popover-link" data-content="Benylin Chesty Coughs UK MHRA Product Information" href="#reference-F3394">18</a></sup>. Following a 50 mg oral dose of diphenhydramine, the volume of distribution is in the range of 3.3 - 6.8 l/kg <sup class="text-reference-group"><a class="reference-popover-link" data-content="Benylin Chesty Coughs UK MHRA Product Information" href="#reference-F3394">18</a></sup>.</p>