Is it common to have breast tenderness & tiredness as early as 6 days after having sex? what's the earliest you can have pregnancy symptoms?

May be normal cycle: Those symptoms are also typical premenstrual signs. Take a home pregnancy test if you think you might be pregnant.

Uncommon: It would be very unlikely after only 6 days. It days 2-7 days for the fertilized egg to implant, then several days for the pregnancy hormones to start increasing - hcg, progesterone, etc. Most people dont have symptoms until 2-4 weeks post-sexual activity. Good Luck! Dr. S