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Herb-drug Interaction With Mexiletine

by jodivt - February 19, 2026

"Sadie" 14 1/2 yr FS pitX canine
In 2024 she had surgery to remove a bladder polyp which was causing recurrent UTI. Sadie has a more recent history of urine leaking during sleep and sometimes awake, large volumes and unaware. Has had episodes of "spacing out" and reluctance to step down of of curbs, like she had difficulty seeing. She was also wandering and restless at night. She had a vestibular event in 2/2025 which has resolved except for a very slight head tilt. History of chronic stifle disease. Diagnosed with T cell lymphoma in 2025 which has been stable, not requiring and conventional treatment other than regular oncology checks.
The urine leaking and cognitive signs have resolved with Xiao Chai Hu Tang, Ba Zhen Tang, ThorneVet Cognitive Support and Real Mushroom;s lions mane mushroom supplement.
Recently she presented for routine acupuncture and the owner noted Sadie was sleeping more and just seemed tired. Tongue red and moist.
Pulse L At the last AP treatment last week, tongue was pink-red, moist, no coating. pulses had slight tone, mid-depth after AP treatment: LI4B BL23 BL25 BL28 GB27 GV2 GV1 BL40 ST36 KID3B
TCM diagnosis is TBO, with Damp. Heart Qi-Yin deficiency
Since then the sotalol dose has been adjusted based on the presence of AV block to the current dose of 60 mg in the am and 40 mg in the pm.
Followup EKG this week showed first degree AV block and uncontrolled AVCM. She was started on 150 mg mexiletine PO 2 8 hours.
I have not used this drug before. I had continued the XCHT, but held it back since I was unsure of any herb-drug reactions. XCHT seemed to do well with the sotalol, but wanted to check and see if you could provide information on any herb-drug interactions with mexiletine and XCHT.
I had also thought about Xue Fu Zhu Yu Tang. Your thoughts?
Thank you

by naturevet

February 23, 2026

Hi Jodi,

There are (apparently) no reported HDIs between the herbs you have used or are considering using. The cytochrome that metabolizes the drug is apparently affected by Echinacea, but no other herbs, per a recent systematic review of the literature. So, you're safe to proceed however you would like to.

Congratulations on your success to date. The improvement on XCHT and Ba Zhen Tang clearly suggests a Shao Yang Disharmony complicated by Yin deficiency. Neither formula really touches Heart Fire, though, which is suggested by the red tongue and tachyarrhythmias.

Given the history of vestibular syndrome, we can conclude the main manifestation of the Shao Yang disharmony is now Yang rising, calling for Chai Hu Jia Long Gu Mu Li Tang. You could add that in, or replace XCHT with it. It works fine with Yin tonics. I usually use Yi Guan Jian with it, as the latter also calms heart tachyarrhythmias to a certain extent.

The two products are sold in one bottle as Halscion from Gold Standard Herbs. You can source those readily in Canada, Australia and the USA. You may not need the Ba Zhen Tang if you use YGJ instead.

Hopefully, this helps you out!

Steve

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