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Why would I need a double dose of Levonorgestrel?

Why would I need a double dose of Levonorgestrel?

Levonorgestrel is a synthetic version of the hormone progesterone. It’s used as a type of emergency contraception (often under the brand name Prevenelle or Norlevo) and can be taken after unprotected sex to prevent pregnancy. 

It’s thought that levonorgestrel works by stopping or delaying the release of an egg. To do this effectively, however, it needs to be taken within 72 hours (three days) of unprotected sex – and ideally within 12 hours.

Most women who take levonorgestrel will need to take exactly one pill, but some might be instructed by their doctor or pharmacist to “double up” by taking two. Read on to find out why.

Reasons for taking a double dose of levonorgestrel

The standard Levonorgestrel dose is 1.5 milligrams (mg). However, some people might need double that dosage i.e. 3 milligrams (mg). There are a few reasons why your doctor or nurse might prescribe this double dose of the morning after pill, including the following. 


You might need a double dose of levonorgestrel if you weigh over 70 kilograms or have a BMI over 26. This is because having a higher bodyweight or BMI is thought to reduce the effectiveness of oral emergency contraceptives. 


There are several types of medication that can prevent levonorgestrel from working properly. If you’re taking medicine for any of the following conditions, you should tell your pharmacist or doctor:

  • Epilepsy
  • Tuberculosis
  • HIV
  • Fungal infections

You should also tell them if you’re taking anything that contains the herbal remedy St John’s wort

Depending on the medications you’ve been taking, you might need to double up on your dose of levonorgestrel. 


Another reason for taking two levonorgestrel pills is sickness. If you vomit within two hours of taking levonorgestrel, you’ll need to go back to your pharmacist or doctor to take another tablet or get advice about alternative emergency contraception.

Alternatives to levonorgestrel

Levonorgestrel is probably the best known type of emergency contraception, and it’s usually the type that’s easiest to obtain. However, it won’t be right for all women. 

The good news is, there are two alternative types of emergency contraception you can get for free on the NHS:

  • ellaOne – another type of emergency contraceptive pill that contains ulipristal acetate
  • The copper coil or IUD – a small, T-shaped device made from plastic and copper that is inserted into the uterus

Advantages and disadvantages of ellaOne

The advantages of ellaOne are that it can be taken up to five days after unprotected sex, and it’s generally thought to be more effective in preventing pregnancy than levonorgestrel. 

Like levonorgestrel, it’s readily available at pharmacies and through services like Online Doctor. It’s also very easy to take, and doesn’t require an appointment with a healthcare professional.

However, this type of morning after pill also has its downsides:

  • You can’t take ellaOne if you’re taking certain types of medication e.g. those for epilepsy, HIV and tuberculosis 
  • You shouldn’t breastfeed for a week after taking ellaOne
  • You’ll need to take a second tablet if you throw up within three hours of taking ellaOne

Advantages and disadvantages of the copper coil

There are two clear advantages to using the copper coil/IUD as emergency contraception:

  • It’s the most effective type of emergency contraception
  • It can be left in and be used as ongoing contraception for several years

However, unlike the morning after pill, the IUD requires an appointment with your GP or with a sexual health or contraception clinic. This is because the coil has to be fitted by a healthcare professional. The procedure doesn’t take long, but it can be uncomfortable and even painful for some women.

What to do after unprotected sex

If you’ve had unprotected sex in the last couple of days and you don’t want to get pregnant, the best thing to do is get medical advice as soon as possible. You can get advice about emergency contraception from the following places:

  • Your GP surgery
  • Contraception clinics
  • Sexual health/GUM clinics
  • NHS walk-in centres & minor injuries units
  • Pharmacies

It’s normal to be worried and unsure about what you need to do, but the good news is, you don’t have to make a decision about emergency contraception yourself. The healthcare professional you speak to will make sure you get what’s safe and effective for your body.

If you already know that you’d like to try the morning after pill, you can use Online Doctor to order ellaOne or Levonorgestrel. We’ll ask you to fill out a short, confidential questionnaire for our in-house doctors to look at – if they think you might need a double dose of the morning after pill, or a different type of emergency contraception, they’ll let you know.

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Authors and editors

Reviewed and updated by: Our clinical team Date reviewed: 23-08-2023