The more common, milder side effects usually settle as your body adjusts or the dose is refined: breast tenderness, spotting or breakthrough bleeding, headache, nausea, skin irritation where you apply it, and bloating. There is no good evidence that biest cream reliably causes weight gain; menopause itself shifts body composition, which is often what gets blamed on the cream.
The serious risks are the established ones for estrogen-containing hormone therapy: blood clots, stroke, and breast cancer. Risk depends on your age, health history, the type and route of hormone, and how long you use it. A physician reviews your history, including any personal or family history of clots, stroke, or hormone-sensitive cancers, before prescribing.
On the evidence: compounded creams are not standardized the way an FDA-approved patch is. The one randomized pharmacokinetic trial most often cited (Sood et al., Maturitas, 2013) found compounded creams generally delivered less estradiol into the bloodstream than a standard patch. That is the practical reason a conservative starter is titrated upward rather than assumed to be "enough."
One thing we state plainly: compounded biest cream is not FDA-approved. The active ingredients (estradiol and estriol) are long-established, but the compounded preparation itself is made for an individual patient and is not reviewed by the FDA as a standardized product. Major bodies, including ACOG and The Menopause Society, prefer FDA-approved hormone therapy where an equivalent option exists.
