Hi, thanks for your question. This sounds tough. As Dr Webberley says, there are so many causes of changed mood in teenager, so it is of course worth exploring all the different possibilities of what is causing the problem.
However, regarding the pill specifically, many pills do have altered mood as a documented side effect. I don't think Gildess is something that is commonly prescribed in the UK, so I can't get access to the official information about this, but if you look at other combined contraceptive pills (which are the same "type" of pill as Gildess), then mood swings etc. are a common side effect. For example, if you look at the patient leaflet for Microgynon, which is one of the most common UK pills, you will see that mood swings is one of the most common side effects:
http://www.medicines.org.uk/emc/PIL.3440.latest.pdfLots of women feel that the pill gives them different side effects, and some of these include changes in mood. However, there are lots of different types of contraception, and different formulations, so she may be able to try something different if she asks her GP.
Going back to the original problem of "pre-menstrual syndrome" i.e. mood changes before a period, let's look at the UK guidelines on how to treat this (from "NICE"). Did you try any of the following? Maybe these would help with the pre-period mood swings:
- Regular, frequent (2–3 hourly), small, balanced meals rich in complex carbohydrates.
- Regular exercise.
- Regular sleep.
- Stress reduction (maybe ensure everything is OK with school/uni, exams, money, friends/relationships?)
- Smoking cessation and restricting alcohol (if relevant)
- Ensuring good pain relief if she has bad period pain or breast pain which may affect mood
I hope she gets on OK and you can get to the bottom of what is happening.