If you accidentally take two birth control pills in one day, it is not a cause for alarm and most likely wont have any serious health effects. However, you may feel slightly nauseous that day, but the feeling will pass quickly. You should continue taking the rest of your pills as usual, once a day at the same time every day for the remainder of the pack. If you miss a pill, take it as soon as you remember, even if that means taking two pills in one day. If youre more than three hours late to take a pill or miss any number of pills, youll need to use a backup form of birth control for two days. If youre concerned or experience severe symptoms, you can talk to your pharmacist or GP, or contact NHS 111.