Dr. Irfan Siddique provides a simple explanation of the common side effects of the medication and how you can manage them: It is a skin patch used to manage menopausal symptoms (thus, acting as a form of hormone replacement therapy). As it contains oestrogen, it can cause weight changes, fluid retention, and vaginal thrush. Moreover, it can also cause skin rash 9at the site of patch), increased tiredness, feeling sick, or abdominal pain. Prolonged use of HRT, itself, can also slightly increase the risk of breast and uterine cancer. So, a healthcare professional usually weighs the risks vs. benefits for HRT before starting them.