Make a new date with him; he will understand when you explain why. If I were your date, and you showed up sick like that, it would be a very short first (and only) date. Going out with someone when you're that sick is a sign of bad choices.

Actually, if it works out, sounds like a magnificent thing to reminisce on in the future

Reschedule if you aren't feeling well. He'll understand if he's a keeper.

I had this happen a few weeks ago, no joke. We met on a dating site and were planning to meet for coffee, but I'd completely lost my voice from singing Disney songs too loudly with a sore throat a couple of days earlier. I just texted him before the date to let him know I sounded like a rusty chainsaw and he just laughed and said "as long as you don't sound like one normally" (and he found the Disney song explanation pretty amusing). If he's a good guy then he won't be put off by something so trivial.

Just an update (after we rescheduled the date): We finally had our date, and it turned out that he too had lost most of his voice from a cold, but it all seemed to go well and we got along great. We're hoping to have a second date but preferably once we've both fully recovered and are done honking every time we laugh.