What are the possible complications and side effects of a brow lift?

The types of complications that are possible are directly a result of which browlift technique is chosen.
If you have a coronal lift, the chance is 100% that you will lose sensation from the deep branch of the supraorbital nerve. Hair loss and numbness are common.
If you have an endoscopic forehead / midface lift, there is a higher chance of injuring the nerve to the forehead (frontal branch).
If you have a hairline browlift, there is a higher chance for visible scars.
If you have a behind the hairline lift, or an endoscopic lift, the chance of baldness around the incisions is higher, and so on.
No browlift is right for every patient, and they all come with a series of pros and cons.
You may wish to read our book chapter on browlifting techniques in the textbook Mathes.

Many of the risks associated with brow lifting are similar to other surgical procedures, but there are a few unique risks involved. Bleeding, scarring, infection, numbness, nerve weakness, bruising, swelling, pain, and hair loss are all possible, but most of these are uncommon. Bruising, swelling, short-term discomfort, and temporary numbness are all to be expected. The degree to which each of these occurs for each patient will vary depending on the patient and the particular brow lifting technique used by the surgeon.All the best

Complications associated with
browlift surgery are fortunately uncommon.  When complications occur, they are often related to the type
of browlift incision used.

When an open approach is utilized,
problems with numbness hair loss and scarring can occur.  When endoscopic browlift is performed,
the nerves that elevate the brow can be damaged.  Both of these procedures are associated with elevation of
the hairline as well.  Hairline
incisions avoid this problem, but may also be associated with noticeable
scarring.

With any surgical procedure,
infection, bleeding, hematoma formation and swelling can also occur.

It’s important to understand that
no two patients are the same. 
Complications with browlift surgery can be minimized by carefully
selecting the appropriate incision for each individual patient.  This
individualized approach has resulted in a low complication rate for browlift
surgery.