Can doxycycline cause a fasle negative pregnancy test?

No. If you have any concerns, get a blood test for HCG level.
No. There's no evidence that Doxycycline can cause a false negative pregnancy test. It may, however, cause erroneous results on urine sugar tests.

Related Questions

Is it possible to have non ectopic pregnancy on Mirena (levonorgestrel) I.U.D.? And would it cause a negative pregnancy test?

Mirena (levonorgestrel) IUD/Ectopics. An intrauterine pregnancy is almost impossible to implant if the Mirena (levonorgestrel) IUD is not expired. An ectopic pregnancy in another location like Fallopian tube or peritoneum is more likely, but not with repeated negative pregnancy tests and no other symptoms. Read more...

What could cause no period yet and a negative pregnancy test?

Many things. At your age peri-menopause, it is not abnormal to start skippimng periods at your age, your gyn can do hormone blood tests like fsh, lh to see if they are getting elevated as well as other blood tests and an ultrasound. Read more...

My menstrual cycle is late and I have a negative pregnancy test. What are causes for this?

See below. Menstrual irregularities are not uncommon. Anovulatory cycle is a common explanation. For more information, please consult this site. Read more...