Brief Answer:
Kindly read ahead

Detailed Answer:
Hello,
Thanks for posting in HCM.
I read your question and understood your problem.
As you mentioned you have just gargled with a cup of dettol and not ingested or swallowed it.
Dettol if ingested can have serious health effects but as it was only gargled and spit out it shouldn't cause any bad effect.
Good thing you washed mouth immediately and rinsed with listerine so any remnant of dettol in mouth will also be taken care of.
I do not see any bad consequences after seeing the amount you gargled with the immediate measures you took.
So you can relax. If you having the bad taste you can take some sugar to overcome it. That should suffice mostly.
Hope this answers your question.
If you have any questions kindly ask me back.
Thank you

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