Actress Susan Penhaligon said Botox left her looking like a "character in Planet Of The Apes".
The star, once known as the "British Bardot", decided to have the cosmetic treatment after turning 60 in July.
Penhaligon, who shot to fame in the 1970s comedy No Sex Please: We're British and the drama Bouquet Of Barbed Wire, said: "I was a complete wally to have it in the first place.
"It very nearly had a disastrous effect on my career and on my confidence as a person. I will never go near it again. I'm simply going to let nature do what it will to me."
The star, who recently appeared in Emmerdale, told the Daily Telegraph: "For many years, I never considered that I needed anything like Botox.
"I thought it wasn't necessary for me because I'm an actress and need all my expressions. It also seemed to me that it was something only Americans had.
"But it has become increasingly acceptable and as I noticed more and more people having it, I got interested in it and started thinking 'Shall I have it to help me get work, or shan't I?'.
"When I woke up on my birthday this year I thought 'How did I get to be 60?'. Yet I actually looked pretty good for 60, and 60 is not what it was in my mother's day."
Penhaligon visited a clinic "on a whim" and was later given injections by a fully-qualified cosmetic doctor who told her she would be very pleased with the results.
But she woke the next day with a terrible headache and said: "I looked in the mirror and saw, to my horror, that my eyebrows had dropped, pushing my eyelids down. I resembled Roddy McDowall's character in Planet Of The Apes."
After returning to the clinic for more Botox to "adjust" her appearance, she "was even heavier on the brow, not unlike Frankenstein's monster", she said.
The star discovered on the internet that she has so-called "droopy eye" or "droopy brows", which affects around 1% of people who have Botox, when the brow drops over the eyelids.
Sir Cliff Richard has also said that he tried Botox but decided to steer clear of more treatments after his "eyebrows dropped".