Did you know that antibiotics could affect the menstrual cycle? Indeed, most of them can have an effect on menstrual periods, with some reporting delays. Find out more about the connections between antibiotics and the menstrual cycle below.
Your Regular Cycle
During the first 14 days of a 28-day menstrual cycle, your follicle will start to grow and kick-start the initial production of additional estrogen. It will start to make the endometrium lining thicker. When ovulation commences, the estrogen hormone will be joined by the progesterone hormone from the corpus luteum to make the endometrium mature and thicker.
How Antibiotics Affect the Normal Cycle
Antibiotics can interfere with your body’s mechanism, which secretes the human chorionic gonadotrophin hormone (hCG) and cause uterus shedding to delay your period. This will happen mainly because the available estrogen will be reduced to cause a change in your cycle for it to become irregular.
A study done in 1947 shows that Penicillin caused heavier bleeding, changes in pain and PMS symptoms and the start of the cycle itself, but they stated that they weren’t able to find any correlative information regarding that.
There are actually two ways antibiotics could affect the estrogen metabolism. Most antibiotics are metabolized in the liver, and when they are present, the metabolism rate of estrogen as well as progesterone will be affected. This can interfere with the estrogen supply that is in the blood and causes an irregularity of the menstrual cycle.
In order for the follicular phase of menstruation to occur, the estrogen is needed to stimulate the ovaries and thicken the uterine wall. Without this, ovulation doesn’t happen or it happens late, which obviously affects when your period will arrive.
Other Issues with Antibiotics
There are some antibiotics that will cause diarrhea-like symptoms when they interfere with the stomach flora.
Even though it’s supposed to kill the bad bacteria in the body, it also affects and kills the good bacteria as well, which is why some women report yeast infections as well after their use of antibiotics.
The entero-hepatic circulation will be affected and cause a reduction of estrogen levels in the blood. It’s becausegut bacteria that usually re-activates small amount of estrogen in intestine are no longer available [1].
When the estrogen levels change in the blood, your cycle will be affected low estrogen levels fail to stimulate pituitary release of hormones. Your body actually ovulates based on the pituitary gland’s ability to identify that sufficient estrogen is in the blood, and then cause LH surge which causes ovulation on 14th day of cycle. So antibiotic treatment can affect these delicate hormonal balances.
So your body doesn’t have enough estrogen to regulate normal menstrual cycle.
Another important point to note is that antibiotics change your body’s metabolic performance and the ability to sustain a steady hormone level.
Use the Second Form of Protection if you are Not Trying to Get Pregnant
Antibiotics can also affect the estrogen as well as progestin levels in oral contraceptive pills. Estrogen is actually an active ingredient in these pills and the antibiotics will affect how it’s metabolized in the body.
Rifampicin and Rifabutin are liver enzyme-inducing drugs and can clear the estrogens from blood at faster rate thereby reducing the contraceptive benefit anticipated from contraceptive pills.
You should get medical advice if you are taking antibiotics in the first seven days of a new pill packet and you engage in sexual intercourse in the last five to seven days. The antibiotics could disrupt the normal protection that the pills provide and cause you to get pregnant.
So if you are taking antibiotics, ensure that you are also protecting yourself as well if you are not looking to have another child right now.
Reasons other than antibiotics that affect your period
While antibiotics get a bad rap regarding the effect on the body and the menstrual cycle, there can be other potential issues and situations that can go on with the body during the time frame. When sick, antibiotics or not, the body is being stressed to the max.
It is trying to accommodate for being sick and the stress of still having to maintain a home, a job, children, a spouse (because you know, moms don’t take sick days). So take into consideration that it can be affected by the meds or by stress, weight loss or gain, usage of birth control, and PCOS or thyroid conditions.
How to Prevent Antibiotic Related Period Issues
One way to help balance your hormones while you are on antibiotics could be to switch up your diet while you are taking antibiotics (and after as well if you are looking to maintain a healthy balance).
In order to balance the estrogen levels, you can add some fish oil, vitamin D, and vitamin B to your diet as well as probiotics, which can help balance that gut bacteria in a beneficial way.
Plus you’ll want to get enough sleep (which helps so many bodily systems) and be stress free (see above).
In general, antibiotics can affect so many bodily systems. Know that they shouldn’t be something that you take on a regular basis because it can cause antibiotic resistance in the body.
Take them only if necessary and ensure that you take the proper precautions for preventing pregnancy and keeping your other systems in balance.
If your period is still late, however, take a test and be confident with the results. But if you are still concerned with what is going on, be sure to talk to your doctor if you need more information on the effects of antibiotics and menstrual cycle.
References
- Estrogen-gut microbiome axis: Physiological and clinical implications. https://www.ncbi.nlm.nih.gov/pubmed/28778332
Hellow
My case is i used levofloxacin on 3rd may i have throat ulcer….my period was supposed to start 20th may according to my calendar but suprisingly enough i haven’t seen my period this is a 2nd week (9days late)
Could the reason of my delay be from the drugs i took in the beginning of this month..????
Hello Jessy, the antibiotics might have delayed your period.
Hello, my period has always bn regular. I was placed on Zinnat antibiotics for an infection and my period is delayed by 9days now. Kinda worried
Hello there Mama, antibiotics are known for delaying a woman’s period.
Two weeks ago I was prescribed metronidazole ( 2 pills a day for 7 days), last Thursday I finished taking the medication. I had unprotected sex on April 23rd and also May 4th. My period is now 3 days late and pregnancy test is negative (though I have several other signs of early pregnancy). Could the metronidazole have just caused my cycle to be delayed? Or could I be pregnant and need to retake a test in a few days?
Hello Tammy, yes the antibiotic mentioned might be the reason for your period being delayed.
My doctor gave me cephalexin 4 times a day for 7 days for a bite that was getting bad but i haven’t had sex. I may have came in contact with some sperm. I’m two months late.
Hi Maria, while the antibiotics could have delayed your period by a bit, I would talk to your doctor. Two months without a period seems to be a significant amount of time (especially if you aren’t on hormonal birth control). Now you say that you haven’t had sex but that you “may have come in contact with sperm” so depending on what that means, I would take a pregnancy test first and then contact your doctor.
hello..I had UTI which I was given nitrofurantoin and augmentin..is still not going away. I have been having a light period since February and it was confirmed I am not pregnant nor infected. What could be the cause.
Hi Bernerdict, if you are still bleeding, since February, I would recommend another appointment with your doctor. Bleeding for that long is something that one should not take lightly. They can hopefully get your cycle back on track.
Hi,
Was on ciprofloxacin and metronidazole for treatment of infection, was supposed to have my period on the 14th and it is still not here. Though I have taken home pregnancy test and it’s negative. Could it be the antibiotics?
Hi Brianna, between the infection and the medications your period could definitely be delayed and affected. Our bodies are sensitive to change and are very good at shutting down the reproductive parts when the body is not healthy enough. I would give it some time (however we are now some time since then) and if you have’t gotten your period by the second month I would call your doctor.
Thank you so much Daniella, got my period last month. But it’s late again this month, went to the doctor but I was told no cause for alarm. I really want to get pregnant. Really worried
Hi Good evening. I took azithromycine to treat RTI .The first day I take it in the morning and I was also fasting at the same time but in the evening I saw blood thinking I’ve menstrated but the blood didn’t come again till my due time for mensuration and it also was delayed. Please am I having any problems? Thank you.
Hi Hannah, Doesn’t sound like it. Taking an antibiotic can affect your cycle enough hat it may be delayed for a bit. Your body is fighting a lot of things at once so it will cause your period to be later sometimes. If you have gotten your cycle since then you should be good.
Hi please I suppose to get my menses on 13th of this month but hv not yet received I did a pregnancy text and was negative. I was having candida so I took in some antibiotics including ciprolex tz. Is it becos of the antibiotics dat has delayed my menses
Hello Mawunam, yes the antibiotics might be responsible for delaying your period.
Hello.. I had sex the day before I started treating infection with antibiotics, suppose to start my period on the 10th of this month but it didn’t come… And it has been 18 days late now Have done pregnancy test twice and it’s been negative,
Is there any way I’m pregnant..
Hello Emmy, the delay might be due to you taking the antibiotics. This might have delayed your period.
Can I use antibiotics while menstruating?
Hello Ose, see your doctor about this based on the condition you are treating,
Hello. My doctor prescribed norgestimate and ethinyl estradiol to correct my irregular menstrual cycle and also to stop my bleeding because I bleed for more than a week. Two weeks later I went to see a skin doctor because of the dark spots and ingrown hairs on my face. The doctor place me on amoxicillin 875mg. Two after starting this medication, I started bleeding heavily again. Please do you know why this happened?
Hello there Heavenly King, you need to see another doctor to get a second opinion. Or see your doctor again for further tests and medical assessment.
Alright. Thank you Alison.
Hello.. I had sex the day I was suppose to start my period but it didn’t come… And it has been 6 days late now .. is there any way I’m pregnant.. I took beecham ampiclox a week ago..
Hello there Dee dee, antibiotics delay the period, this might be the reason for the delay in the starting of your period.
Hi,
I’ve been taking doxycycline for MRSA for a few weeks now and I’ve missed my period. It’s usually very regular (I’m on the pill) so it’s super unusual. I had unprotected sex before my last period and I still got it, so I concluded I wasn’t pregnant. But now I’m worried that I am. I haven’t had sex since then and the only other thing I could put it down to is that I’m on doxycycline now. Do you think that’s what has made me skip a period?
Hi there Becky, yes, antibiotics do delay the period. However if you think you might be pregnant then take a pregnancy test to determine same.
Hi, I had unprotected sex for 7 days and took
ampiclox for that 7 days, and my period is delaying, but I am having a sign of it.
Hi, am Susana
I was injected with cefuroxime injection since the injection, my menstruation was not flowing that much ,what can be the cause.
Hi Susana, antibiotics can delay your period or cause changes to it. I wouldn’t be too concerned if your period is late or different than it usually is.
Hi! I was prescribed doxycycline twice a day to treat Lyme disease (acute stage). My period was due a few days after I started the course (15 days ago) but never came. I have another 15 days to go with this intense treatment. I assume the combo of Lyme and antibiotics can delay it, but just wondering if this is normal or if my cycle should regulate when the antibiotic regime is over. Thanks.
Hi Pam, most likely your period will regulate after you start your next cycle. The combination of being sick and taking antibiotics does affect your cycle and can delay it. I would still take a pregnancy test though just to be sure.
Thank you! Also, silly question, is there any way doxycycline could cause a false negative pregnancy test or does it just tend to delay your period? I’ve been getting negative tests but haven’t tested in about a week. Thanks again!
Hi Pam, No. False positives don’t generally happen unless it’s a faulty test or your weren’t far enough along for the hormones to be detected. The medications will only tend to delay your period and nothing more.