Pharmacy tests are great! A real modern convenience for anyone trying to get pregnant, right? However, they can sometimes come with headaches in some unusual situations. One of the many situations that can happen with home test use is the occurrence of false positives.

These occurrences can make any trying woman pull her hair out, right? The doubt over which result to trust is tough and can confuse a lot of people. So how about figuring out why a pharmacy test comes back positive while the blood test is negative?

One of the main reasons a pharmacy test gives a positive result while the blood test is negative is the amount of HCG present in a woman’s body. Some tests can be so sensitive that they are even more efficient1 than the blood test! Of course, this factor is a double-edged sword, because for this to happen, the laboratory’s minimum sensitivity must be the highest, in other words, 50mIU. Some brands have a minimum sensitivity of 10mIU, so any amount close to or above this would theoretically be detected, such as the Famivita pregnancy test which you can buy here in our online store. We should also consider how dark the test line is; if it’s very faint, it could indicate a very early pregnancy.

The risk of taking the test before your period is due should also be considered2. Some laboratories that run the qualitative beta HCG might not consider a slight positive from the blood test (faint line) as actually positive. In fact, most laboratories only determine a result as positive when it’s absolutely clear the result is positive. In these cases where there’s doubt, it’s likely they will recommend that the woman repeat the test in a few days.

The recommended approach in all cases is to repeat the beta HCG test in a week. The laboratory itself advises women to retake it to see if the amount of HCG in the body increases. If the hormone levels go up, then the result becomes considered positive. But if it continues to be negative, there’s probably something wrong with the pregnancy tests. When can a test be wrong?

When Is There Something Wrong If the Pharmacy Test Is Positive and the Beta Is Negative?

One situation that can happen with these tests is that the pharmacy test detects another hormone in the body that has the same structure as HCG: LH! This phenomenon happens rarely and at certain times in that cycle when this hormone is high, close to the ovulation period which for many women is about the middle of the cycle. Theoretically, at the end of the cycle it wouldn’t be possible to get this positive result from LH as ovulation would have occurred some days before, but it’s possible for the hormone to be out of balance, causing this positive result.

Another factor that can give a positive result on the pharmacy test and a negative on the blood test is the use of medications that contain HCG and are eliminated in the urine. Some women use certain substances used to treat fertility (to rupture eggs) such as Choriamon, Choragon, and Ovidrel. Other medications wouldn’t interfere with pregnancy test results, such as the morning after pill, for example. They do not have the ability to produce HCG. This hormone is exclusive to pregnancy or can be ingested in some medications.

There’s also a chance that the pharmacy pregnancy test itself could have some kind of problem3. Some brands may frequently give false positives for various women on different occasions. To clear up whether your test was a false positive or not, it’s advised to do another one from another trusted brand. If the test keeps coming up positive and the beta remains negative after 15 days, it’s best to see a doctor to check what’s really happening.

See also: Can I Take a Pregnancy Test Before My Period Is Late?