5-FU injections after blepharoplasty to reduce scar tissue?

The redness, dryness, and darkened skin around the injection site after 5-FU treatment post-blepharoplasty is usually temporary. However, since you are Fitzpatrick skin type 1, your skin is quite fair and can be more reactive or sensitive.
5-FU injections can cause local irritation and may lead to temporary hyperpigmentation—or, less commonly, hypopigmentation. Three weeks post-injection is still within a normal healing window, but this process can sometimes take several weeks or even months.
If the discoloration hasn’t improved or seems to be worsening, I would recommend following up with your surgeon or a dermatologist for evaluation. In the meantime, sun protection is crucial. Use a broad-spectrum sunscreen daily to help prevent the pigmentation from becoming permanent. Your doctor may also suggest topical treatments or lightening creams if needed.