How do I take Levonelle? Levonelle should be taken within 72 hours of intercourse. The sooner it is taken the more effective it is. Levonelle is a single pill which can be taken at any time of day at any point in your period. You should not take Levonelle if you have had sex more than 72 hours previously. Cautions Levonelle only helps to prevent pregnancy not STI’s. It should not be used as a contraceptive method as it is intended for one-off use. Levonelle can interfere with the contraceptive pill and although you should continue taking your contraceptive pill , barrier protection will need to be taken for up to seven days afterwards. EllaOne is slightly more effective than Levonelle especially in women who are over weight. If your BMI is over 30 you should take ellaOne rather than Levonelle. If vomiting occurs within three hours of taking a tablet the dose should be repeated. Periods may come early or be delayed after taking a morning after pill. If a period is more than 5 days late a pregnancy test is required.