How long before I will know if steroids damage my facelift?

Oral steroids can sometimes be used to help reduce swelling after a facelift, although I do not routinely prescribe them. With short courses, there should not be any effect on the longevity or long-term results of a facelift. Injectable steroids can be used to break up or soften scar tissue and should not affect the long-term results either. For patients who are placed on long-term oral steroid treatment for other medical issues, there are many complex changes that can occur which can affect the shape of the face and alter the appearance of the body. This does not necessarily ruin the result of the facelift, but will likely change a persons overall appearance. 

With proper technique, steroid injections should not cause damage to the results of your facelift. In general, high concentrations of steroids injected over a prolonged period of time, or too superficially into the skin, can induce skin atrophy and loss of pigmentation. However, steroids are meant to serve a beneficial role when used as an adjunct during the recovery time. Hope this helps.

I am not certain if you are referring to steroids being taken orally or injected in regards to your question about possible damage to your facelift.  In general, steroids used for medical purposes should not necessarily be damaging to a facelift.  Some surgeons may give intravenous or oral steroids to cosmetic surgery patients to try and decrease swelling and inflammation.  After surgery, some surgeons may use injectable steroids to improve certain types of scarring.