You can start feeling pregnancy‑related nausea surprisingly early, often before you even miss your period, but there’s a typical window when it shows up for most people.

Quick Scoop

  • Nausea from pregnancy (often called “morning sickness”) usually starts between 4 and 6 weeks of pregnancy.
  • Some people notice mild nausea as early as about 2 weeks after conception (around 4 weeks pregnant).
  • Symptoms often peak around 8–10 weeks and usually start easing by 12–16 weeks.
  • A small group continue to feel nauseated well into the second or even third trimester.

So in terms of “how soon” after conception: nausea can realistically appear about 2–4 weeks after conception , but for most people it becomes noticeable around week 6 of pregnancy.

What “weeks” actually mean

Pregnancy weeks are usually counted from the first day of your last menstrual period (LMP) , not from the exact day of conception.

  • Conception typically happens about 2 weeks after LMP.
  • When you’re “4 weeks pregnant,” conception was roughly 2 weeks ago.
  • Many people start to feel nausea around the time of, or shortly after, the first missed period (about 4–6 weeks pregnant).

That’s why it can feel like nausea shows up “very soon” after unprotected sex, even though doctors call that 4–6 weeks pregnant.

How long nausea lasts

  • Most pregnant people have symptoms improve or disappear between 12 and 16 weeks.
  • Up to about 10–15% may have nausea that lasts to 20 weeks or all pregnancy.

If nausea is severe (you can’t keep fluids down, you’re losing weight, feeling dizzy or faint), that can be a sign of hyperemesis gravidarum , which needs medical care.

If you think you might be pregnant

If your nausea:

  • Comes with a missed period ,
  • Started within the last few weeks after unprotected sex , or
  • Is paired with breast tenderness, fatigue, or frequent urination ,

then a home pregnancy test and a chat with a healthcare professional are good next steps.

If you tell me roughly when your last period started and when you had unprotected sex, I can help you estimate how many weeks pregnant you’d be and whether nausea timing fits that. Information gathered from public forums or data available on the internet and portrayed here.