Almost every medication can have side effects, and the same is true for HRT. The side effects can be due to the change in hormones, and to the way your body reacts to this change.
The common side effects such as headaches, bloating or breast pain are usually transient and settle within 3 months. Sometimes it is necessary to change the HRT preparation, or dose, to minimise side effects.
Side effects of oestrogen are breast tenderness, legs cramps, skin irritation, bloating, indigestion, nausea and headaches.
Side effects of progesterone are PMS like symptoms, fluid retention, breast tenderness, low mood, bleeding and headaches.
When you start on HRT, or change the dose or preparation it is common to have some new unscheduled bleeding. If this bleeding is not settling after 3 months please speak with a Dr.