Most side effects from Take Action, a levonorgestrel-based emergency contraceptive pill, resolve within 24 to 48 hours. Nausea, the most commonly reported symptom, typically fades within a day. Changes to your menstrual cycle can linger longer, sometimes shifting your next period by a week or more in either direction.
The Most Common Side Effects
Clinical trial data from levonorgestrel emergency contraception shows a clear picture of what to expect. Among nearly 1,000 women studied, the most frequently reported side effects were:
- Menstrual changes: 26%
- Nausea: 23%
- Abdominal pain: 18%
- Fatigue: 17%
- Headache: 17%
- Dizziness: 11%
- Breast tenderness: 11%
These are all tied to the large, concentrated dose of synthetic progesterone your body absorbs at once. Take Action contains 1.5 mg of levonorgestrel, which is significantly more hormone than what’s in a single daily birth control pill. Your body processes this surge relatively quickly, which is why most physical symptoms don’t stick around long.
How Long Each Symptom Typically Lasts
Nausea is usually the first side effect to appear and the first to leave. It tends to peak within a few hours of taking the pill and resolves within 24 hours for most people. Eating a small meal before or right after taking the pill can reduce the intensity. If you vomit within 3 hours of swallowing the pill, the CDC recommends taking another dose as soon as possible, since your body may not have absorbed enough of the medication.
Headache, fatigue, and dizziness generally follow a similar 24-to-48-hour timeline. These symptoms feel similar to what some people experience before their period, which makes sense given that the pill works by flooding your system with a hormone closely related to the one your body naturally produces in the second half of your cycle.
Abdominal pain and cramping can last one to three days. Breast tenderness sometimes persists a bit longer, up to several days, because breast tissue is particularly responsive to hormonal shifts.
What Happens to Your Next Period
Menstrual changes are the most common side effect overall and the one that takes the longest to resolve. The timing of your next period depends largely on where you were in your cycle when you took the pill. If you took it in the first half of your cycle, your period may arrive several days early. If you took it in the second half, it may be delayed by several days to a week.
Some people also experience light spotting or breakthrough bleeding in the days following the pill. This is not a period. It’s a withdrawal bleed caused by the hormonal shift and typically lasts one to three days. Your flow during your next actual period may also be heavier or lighter than usual. These cycle disruptions are temporary and generally normalize by the following month.
If your period is more than a week late, a pregnancy test is a reasonable next step. Take Action is roughly 94% effective when taken within 24 hours, but that drops to about 58% by the 72-hour mark.
Why Side Effects May Feel Stronger for Some People
Your body weight can influence how you process the hormone in Take Action. Research shows that people with a BMI over 30 have a significantly altered response to levonorgestrel. The pill appears to hit a ceiling of effectiveness around 70 kg (about 154 lbs) and may offer little protection above 80 kg (about 176 lbs). This doesn’t necessarily mean side effects will be worse at higher weights. In fact, the opposite may be true: lower blood concentrations of the hormone could mean milder side effects but also reduced effectiveness. If your weight is in this range, a different type of emergency contraception (ulipristal acetate, sold as ella) maintains about 85% effectiveness up to five days and works more reliably across a wider weight range.
People who are sensitive to hormonal birth control in general may notice more intense side effects from Take Action. If you’ve experienced nausea, mood changes, or headaches on hormonal contraceptives before, you’re more likely to feel them with emergency contraception as well.
Symptoms That Need Attention
Mild nausea, cramping, and fatigue are expected and resolve on their own. Severe lower abdominal pain, especially if it’s concentrated on one side, is a different situation entirely. Combined with heavy vaginal bleeding, dizziness, or cold sweats, these can be signs of an ectopic pregnancy, where a fertilized egg implants outside the uterus. This is rare but serious and requires immediate medical evaluation. Take Action does not cause ectopic pregnancies, but it also cannot prevent them.
No Lasting Impact on Fertility
Despite persistent myths, levonorgestrel emergency contraception has no documented effect on future fertility. Safety data spans decades of use worldwide. The hormonal disruption is real but short-lived. Your ovulation pattern, cycle length, and ability to conceive return to baseline within one to two cycles. Using emergency contraception more than once also does not accumulate risk or reduce your chances of becoming pregnant later.