Bad Reaction to Evoxac—Worsened Dry Eye and Decreased Thyroid Levels

My overall dryness has been worse since I had Covid for the second time in December 2024.  Early last year, I was prescribed pilocarpine and had a terrible allergic reaction.  

When I had a rheumatology appointment in October, I requested to try something other than pilocarpine.  I was prescribed Evoxac.  I was excited, since I've heard that it's great.

Evoxac definitely helped the dryness in my mouth.  The problem was that it made my dry eyes worse and caused me to have blurry vision in the evening.  I have had problems with my eyes since early 2025.  I had seen some improvement in the early fall, and Evoxac pretty much wrecked my eyes again.

I have always struggled with my electrolyte levels.  Two different blood pressure medications failed last year because they either dangerously lowered my electrolytes or threw off my levels.  I simply cannot get my blood sodium level above the lower boundary of the normal range.  One blood pressure medication caused my blood sodium level to fall close to a level that would have required hospitalization.

I believe Evoxac impacted my electrolytes.  I've noticed that I get insomnia whenever my electrolytes are off, and I did get insomnia soon after starting Evoxac.

On top of all the other side effects, I am pretty sure that Evoxac impacted my thyroid levels.  I can't have that.

I searched thoroughly online for confirmation that I wasn't the only person who's ever had these reactions to Evoxac.  It seems to be a miracle drug for just about everyone.  I created this blog because my condition just doesn't follow the same pattern as everyone else.  It's baffling.

I scoured the internet for information to substantiate what I believed was happening to me, and I found just about nothing.  This has happened so many times...

I finally turned to AI to see if I could get any confirmation.  Here, I include excerpts from some of my chats with Chat GPT.  These chats occurred over around a two-week-long period, as I tried to figure out why I was having so much trouble with a drug that helps so many people.

I would like for you to search for any adverse thyroid impacts caused by Evoxac.  I would also like you to search online for any anecdotal reports of thyroid levels that could be tied to Evoxac.

I could not find credible clinical case reports, label warnings, or pharmacovigilance signals that link Evoxac (cevimeline) to causing thyroid dysfunction or to interfering with levothyroxine absorption.

Are there any reports of Evoxac making the eyes dry or making them burn?

Yes—there are reports and side-effect listings showing that Evoxac (generic Cevimeline) can cause dry or burning eyes, or other ocular symptoms, though the data suggest these are less common compared to the beneficial effect of increased tears.

ChatGPT also stated:

While the original intent of the drug is to increase secretions (including for eyes) in conditions like Sjögren's syndrome (which cause dry eyes and dry mouth), the side-effect listings show that in some people, the effect may be paradoxical (or perhaps related to other ocular irritation) resulting in "dry, burning, itching" eyes.

Naturally, I would be one of those people.

I'm wondering if—since Evoxac helps the body secrete more moisture—that going off it could impact electrolyte levels and then as a result cause symptoms like a temporary headache.

Evoxac (cevimeline) does alter fluid balance slightly by stimulating glands throughout the body.

ChatGPT also said:

There's no evidence in studies or adverse event databases that stopping Evoxac causes measurable electrolyte disturbances (like hyponatremia or hypokalemia).

Huh.  That's what it thinks.  It should be noted that I didn't think much of ChatGPT's responses.  AI is unreliable, and ChatGPT acts just like a gaslighting doctor who doesn't believe that a patient is having certain side effects.  It was a few days after this exchange that I decided to corner it.

Evoxac is a cholinergic agonist.  What about this?  See link.

https://www.sciencedirect.com/science/article/abs/pii/0196978185901573

The link I gave ChatGPT goes to "Cholinergic and VIPergic effects on thyroid hormone secretion in the mouse."  The study concludes "that basal thyroid hormone secretion is inhibited by both cholinergic activation and blockade."  Since Evoxac is cholinergic, I felt I had my smoking gun.

ChatGPT, behaving in an incredibly dense fashion, continued its spiel about electrolytes, completely ignoring that the link is to a page about thyroid function being impacted by cholinergic agonists.  I continued in my quest to pin down ChatGPT.

I am referring to this excerpt:

"It is concluded that basal thyroid hormone secretion is inhibited by both cholinergic activation and blockade.  Furthermore, TSH-induced thyroid hormone secretion is more sensitive to inhibition with cholinergic stimulation than is VIP-induced thyroid hormone secretion."

And it seems like Evoxac can impact thyroid levels in some fashion.   Isn't that what this means?

Come on, ChatGPT, you can do it...

• Both stimulating and blocking cholinergic receptors can reduce baseline thyroid hormone release (T3/T4).
• When thyroid cells are stimulated by TSH (the pituitary signal to make thyroid hormones), adding cholinergic activation further inhibits that secretion—meaning acetylcholine-like drugs (such as muscarinic agonists) could dampen thyroid output.
• The inhibition didn’t apply equally to all hormonal stimuli: thyroid stimulation via VIP (vasoactive intestinal peptide) was less affected than TSH.

So yes—mechanistically, cholinergic stimulation can suppress thyroid hormone release under some conditions.

ChatGPT added:

In theory, Evoxac could exert a mild inhibitory effect on thyroid hormone secretion, at least transiently or in sensitive individuals.

That’s not necessarily the same as causing hypothyroidism—but if you already have borderline thyroid function or are on levothyroxine, this kind of interference could slightly alter your TSH–T4 feedback balance.

Precisely.  I quit Evoxac five days ago because it messed up the fluid balance in my body.  My eyes became much more dry with Evoxac.  They are now getting better.  Additionally, my thyroid due to Hashimoto's is extremely sensitive to any medication changes of any kind.  Since there is evidence that Evoxac could impact thyroid levels, I believe that happened to me during the two weeks that I took Evoxac.  I have mild symptoms of thyroid imbalance.   It will take my body a couple weeks to return to baseline.

As I recall, it took around six weeks for my eyes to recover from the Evoxac.  As far as my thyroid levels, I then caught a horrible virus and have still not recovered my thyroid levels as of late April 2026.  But I digress.  That debacle will be addressed in another post.

Anyway, I figured that I had one-upped ChatGPT with my final prompts.  Evoxac was terrible for my body, and I never want to try it again.  It really did help with dry mouth, and I noticed how my mouth was more dry as the medication wore off.  The benefit was not worth the negative symptoms.  I will just continue dealing with my dryness, hoping that one of the new Sjögren's drugs is approved in the next year.  With my luck, I'll be allergic to it.  Still, I can hope.