I started making mead a little over a year ago. Batch #1 was a dry mead with Lalvin 71B-1122 yeast and aged for about 8 months with oak cubes. It clarified on its own and tastes delicious. I used staggered nutrient additions with Fermaid-K and DAP, but nothing too scientific. I just averaged out several sets of instructions that I'd read and it worked out wonderfully. I was so encouraged by the results of the first batch that I invested in several more carboys and other accessories to make the job easier.

Batch #2 was started almost concurrent to the first, but I let it rest without tasting it for a long time because the fermentation had not gone smoothly. I had not yet fully acquainted myself with the details of staggered nutrient addition, and I caused two overflows as well as a strange period of no activity about halfway through primary. The yeast was Wyeast 4632. When I finally got around to bottling it, I was surprised to find that it tasted pretty good. But when I had just one glass, I got a terrible headache right in the front and center of my head. It was within 10 minutes of my first sip and I am not prone to headaches, nor was I at all dehydrated.

By the time I tasted Batch #2 I had already started Batches 3, 4, and 5. They all used Wyeast 4632 and were fermented with pineapple, mint tea, and elderberries respectively. Horrified by the headache I'd experienced, I read about fusels and realized that my poor fermentation control on Batch #2 was probably to blame. I poured out all the bottles and assumed that the other batches would be fine, since they didn't share any of the same complications.

I'm sure you can see where this is going. Fermentation went perfectly for Batches 3,4, and 5 and I tasted them periodically once they were racked into tertiary. They all tasted fantastic, I was thrilled, and I thought that the headache issue was a one-time fusel problem. Again I was encouraged and started Batches 6 and 7. When I finally got around to testing out glasses of Batches 3,4, and 5 I got headaches. They were not nearly as severe as the headaches for Batch #2, but still bad enough that I am sure I will have to pour them out.

For Batches 6 and 7, I adopted a rigorous TOSNA 2.0 protocol and made sure that the ambient temperature was between 63 and 68 degrees F. The yeasts used are Lalvin K1-V116 and Red Star Cote Des Blancs, which both came highly recommended. Fermentation began on 10/21/17, and I just tasted one of the batches tonight. 10 minutes later, headache.

None of the meads that have caused headaches have 'off flavors.' The one tonight was actually very good, especially for its young age. I swear I'm not crazy. I'm not leaving the carboys out in the sun or pouring in DAP or anything. I've been very meticulous!

I have searched every mead and homebrew forum for these instant-onset headaches, and I find few similar stories. What I have found is always attributed to hangovers, dehydration, or fusel alcohols. I'm so frustrated. I know that I entered into the hobby with too much enthusiasm and should have gone about things in a slower and more scientific manner (using several different yeasts has only complicated the issue), but my first batch was somehow a miracle success that I still enjoy drinking without a second thought. I couldn't have expected that every other batch would produce toxic mead!

tl;dr: My first amateur batch turned out great - strong and delicious. Every batch since gives me headaches within minutes of drinking it, and I am not dehydrated.

Has anyone had a similar issue or relevant experiences? Could it be the yeast? Could it be the temperature even if ambient is in the mid-60s? I don't want to give up but I feel like I'm throwing away so much time and money. Thank you all for your help.