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
Hi, I recently was prescribed antibiotics for my uti. My period was expected on August 13, but I am 6 days late now. Could this be because of the antibiotics. Note: I got the antibiotics a week before my expected period.
Hello Angie, yes the antibiotics is the cause for the delay.
My gf have been experiencing short flow of her menstrual period. It’ll come and just flow for maybe one or two days as against three or four days normal flow and she’s not taking any anti biotics. Please what could be the cause(s) and the solution(s) to that?
Hello there Chuks, many women experience a change in their cycle from time to time. This could be as a result of stress, hormonal changes, etc.
HI, I HAD MY LAST PERIOD FROM 15/7-`2/8. DR. PRESCRIBED 2 TYPES OF ANTIBIOTIC FOR ME AS SHE SUSPECTED I HAVE ENDOMETRIOSIS SINCE MY PERIOD LASTS LONG (AROUND 19 DAYS).
AFTER TAKING THE ANTIBIOTIC, MY PERIOD STOPPED ON 3/8.
WHEN CAN I PREDICT MY NEXT MENSTRUAL ?
MY USUAL CYCLE IS BETWEEN 29 – 32 DAYS
Hello Lynn Wee, please use the below link to calculate your next menstrual period: https://womanjunction.com/
I saw my period on Wednesday and I unprotected sex on Thursday and Friday night with my bf and i took postinor 2 on Saturday morning, the question is if I am safe. Thanks
Hi there Temmy, once contraceptive was taken with 72 hours then conception should not have taken place.
I am 8 days late and recently have been in a treatment for 1st degree and 2nd degree burn, Which included antibiotic injections. Could this be the reason my period is delayed.
Hello Amanda, yes, this might be the reason why your period is delayed.
I am currently on depo shots for birth control and was recently treated for tonsillitis. During taking the penicillin for treatment I got my period for the first time in 5 months. Is this due to the meds? I’ve only been taking the penicillin for 4 days.
Hi there Alexis, I cannot determine if this is a period or not.
Can I get pregnant while taking antibiotics?
Hi there Maggy, thanks for your question, kindly see link below:
https://womanjunction.com/antibiotics-increase-risk-miscarriage/
Saw my period last on the 6th of July and up till now have not seen it just worried did a pregnancy test was negative but I took amplicox beecham is it the cause of the delay because all the signs of my period are there.
Hello Zee, yes the use of the antibiotics might be delaying your period.
I have a question, I did an abortion on may 28 and after that week I had an unprotected sex twice but I used postinor 2 and ever since then till now have not seen my period. What should I do, this is July 6 even though I am treating an infection.
Hello Temmy, your comment hints that you are currently taking an antibiotic for an infection, please note that the use of the antibiotics might be delaying your period.
Hello, I’ve been prescribed Doxycycline Hyclate 100 mg tablet for my acne, taken twice a day with food. This is approx almost my second week of taking it regularly. I am on a birth control pill, also have been taking it regularly and have used condom as a second form of protection. I usually get my period On a Tuesday or Wednesday but it’s not always spot on but no period yet… What do your think?
Hello Abbi, Doxycycline Hyclate might be the cause for your delayed period.
Hi there,
I was on injections, 1 in a week for 3 weeks and took metronizadole and doxy in the first week of injection. after 2nd injection I had sex and my period is late? could it be the medicine and if so how long will it be delayed? thanks
Hello Priscilla, yes the injections might have caused the delay.
Hi. On the 10th July I went to see my doctor as I had muscle spasm. He gave me an injection for that. On the 16th I had unprotected intercourse. My period was supposed to come from Thursday now its delayed. Could it be the injection that delayed it or what. I normally have regular periods.
Hello D, you did not mention the type of injection administered. However given the delay in the commencement of your period post injection you should consult your doctor about this.
I am 2 weeks late and I have stopped the antibiotics a week ago
How soon will it be before I start again
I had sex 3-5 days before my last period and the started antibiotics 3 weeks after sex and 2 week after my period
Hi there Amanda, if period does not return within a week’s time then take a pregnancy test.
Hi! I’m expecting my period last July 23 and I’m 6 days delayed. I was given antibiotics for 7 days. Is it the cause of my delay?
Hello Trish, yes this is likely the cause of your delay.
Is it the reason behind my 6-days delayed menstruation? I was confined last July 2 and was discharged July 6, and I was injected Cefuroxime 3x a day for Kidney infection during those days. After having discharged I was advised to take Cefuroxime again orally for 7 days. And after those medication I have unprotected sex since I am in regular period and assume that I am not fertile anymore, I am tracking my period, and we’re using calendar method. I have also taken metronidazole for infection on July 21. My expected period is on July 20. and until now i did not arrived. What will I do? Im pretty worried.
Hello Sharm the taking of such antibiotic might be the reason for your delayed period.
I’ve already missed my period and the pregnancy test says positive. But I somehow hope that the result is brought by my UTI.
Hi! My doctor gave my flagyl for 7 days (last July 9-15) I’m expecting my period last July 18 I’m 6 days delayed. I have a regular cycle. It is because of the antibiotic why I’m delayed?
Hi there Ann, yes the antibiotic is more than likely the reason for your delay.