Plan B or the morning-after pill is an emergency contraceptive pill to prevent pregnancy after unprotected sex. This pill is a quick and effective way of emergency contraception. Although the name suggests a morning-after pill, you shouldn’t wait until morning to take it. Its composition is 1.5mg of levonorgestrel, which is present in many hormonal birth control methods but in lower doses, of course. The consumption window is an important factor that determines its efficacy. The sooner you take it, the more effective it is. If you had unprotected sex within the last 72 hours, preferably the last 24 hours, and don’t want to conceive, Plan B is here to rescue you!
I took Plan B after unprotected sex on January 22nd. Afterwards, I had withdrawal bleeding about a week later, which lasted for about a week. Since then, I did not get my period until June 6th. Since then, I have not gotten a period in July, and it is currently August 10th. Throughout this time, I have taken several pregnancy tests, and they all came back negative. I just wanted to know if this is common, or if there is anything I should do. I will be having blood work and an ultrasound in September to see what is going on. Thank you!
Answered by Dr. Fatima Abbasi, MBBS on August 21, 2026
Thank you for writing in, and for setting out the dates so clearly. You are definitely in a lot of confusion right now, and it is okay to feel this way.
Emergency contraception (levonorgestrel) does unsettle the cycle it’s taken in. It can make the next bleed arrive early or late, heavier or lighter, and can result in a withdrawal-type bleed in the days or weeks afterwards. However, this effect is generally short-lived, usually lasting one to two cycles. So when periods stay away well beyond that window, there can be other causes. Broadly, clinicians tend to think about thyroid function, prolactin levels, PMOS (formerly PCOS), and stress, weight loss, undereating, or a significant increase in exercise. Less commonly, they’ll consider whether the ovaries are winding down earlier than usual. Pregnancy is always excluded first, regardless of the history. Typically, the workup involves blood tests assessing thyroid, prolactin, and reproductive hormones, and a pelvic ultrasound (you already have booked). Your own doctor will decide which of these apply to you.
Here is what might help you during your appointment. You can keep a log of anything that has changed recently, like your weight, sleep, stress, exercise, diet, etc. You can also note the character and flow of the bleed that you have been experiencing. The investigations you’ve arranged are the right step. I hope September gives you some clear answers.