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
Hey I took antibiotics only 3 times in November my last period was Oct 25 never came on in November my period was due the 22 But I took a pregnancy test the yesterday the 4 of December it was neg. could it be the antibiotics
Hi there Ke, yes the antibiotics could be the cause for your delayed period.
Hi, I took cipro and metro pills hoping they will cure my vaginal yeast infection and I started taking them from 10 Nov to 18 Nov and I had protected sex on 10 Nov. Since then I haven’t been on my periods of which I was supposed to go around 24 Nov. I’m getting worried now, can you tell me what’s wrong?
Hello Claire, you took antibiotics which might be responsible for your currently delayed period.
Hello Alison! I started taking antibiotics for skin infection on Nov 9 and I had anal sex on nov 11, I had a pad and I think it leaked but I don’t know if the pad protected it. 3 weeks now My period is 2 days late and I have breast cyst, headache and super bloated stomach and gut problems as well as intense nausea all day. I have extreme anxiety and stress and I’m always shaking and worrying. I don’t know if my late period and symptoms are because of antibiotics, pms or pregnancy. Please help, thank you
Hello Ana, the delay in your period could be as a result of you taking the antibiotics.
I last had my period OCT 12th and I took antibiotics twice on to separate days two weeks after. I did have unprotected sex on NOV 13th and again on NOV 28th. I then experienced a light flow off and on starting on NOV 30th and lasting until Dec. 2nd. Is this just result of the antibiotics?
Hello Lex, this might not be solely because of you taking antibiotics, you mentioned that you had unprotected sex. It could be as a result of this. Please take a pregnancy test 7 days after a missed period.
Hello Alison, I had my period 31st of October then had sex unprotected sex twice while ovulating and once after…but I took antibiotics in all 3 of them…but I was supposed to.get my period on the 1st of December but it’s 2nd now and I still haven’t gotten it though I have signs of my period like my breasts hurt.
Hello Tessy, please take a pregnancy test 7 days after a missed period.
Started amoxicillin 875mg Tuesday my period is 6 days early and I always track my periods and they are always the same. Is it the antibiotic?
Hello Anonymous, yes this could be as a result of the antibiotics.
I took antibiotics for 10 days for strep and 3 days after my last dose my period started which was slightly early. It has been over a week and it still isn’t stopping, what is going on??
Hello Ericka, the antibiotics is more than likely the reason for this.
I had my period on 26th Oct and I have regular cycle now it’s 28th of November and am still not Getting my period. I had lots of injection and antibiotics and lots of antacid due to my gastric problem..during my period days in the previous month and was even on a antibiotic coarse for a week. Is this the reason that is delaying my period? I even had protected sex fr a couple of days. I am very tensed whether some semen got leaked THROUGH the shaft and can make me pregnant or not!( though it is highly unlikely to happen still I am panicked like hell).
Hello Riya, the antibiotics is more than likely the cause for your delayed period.
I had my menses on the 7 October n had unprotected sex on the 11 to 16 October from there had sex again on 19 but I took contraceptive and now I’m pregnant. Please how come?
Hello Chris, you are pregnant because you had unprotected sex during the 11th to the 16th of October. All the best.
Hey alison;
Thanks for the reply. But I had my antibiotics in the first two weeks of my last period and it’s been 5days I am even having a milky nipple discharge surprisingly. Is this anyway affecting my period? Coz m still not having it!
Will be eagerly waiting for your reply.
Thank you!
Hello Riya, please take a pregnancy test 7 days after a missed period.
Hi misty my last period is Oct. 19 we had sex in Nov. 1 and ive been sick on Nov 13to 15 due to difficulty of breathing they gave me antibiotics ceferoxime and salbutamol my next period is Nov 19 but im still not seen my period..
Hello Mary, the use of antibiotic might be the cause of your delayed period.
Hi Alison,
I was on a strong antibiotics the second and third week after my last period. I was supposed to be on my period this week, but it hasn’t come. I’m supposed to start a new BC package tomorrow. I’m wondering if I should just wait to start my BC because I haven’t had my period. Super stressed about it not coming right now.
Thanks!
Hello Annie, the antibiotics may be the reason for your delayed period.
After the delay of not seeing your period because of taking antibiotic ,,,what can someone do to bring it back please??about 5days now am having the symptom but yet to come
Hello Gracy,it will come naturally, just give it some time.
I had sex on the 7th of october and had my period on the 15th of october. Now 3 weeks ago I got chicken pox and I was on a bunch of antibiotics and now I am a week late..
Hello Micah, the anitbiotics might be the cause of this.
I track my ovulation with a well known method, and I recently ended a week long course of amoxicillin. I had unprotected sex a week after I was supposed to be ovulating, and on Sunday (when I was supposed to start my period) it was very light. It’s now Tuesday, and the bleeding is still light, and it’s not like my regular flow at all. I took a pregnancy test today, and it was negative. Could the light period be from the antibiotics? When should I retest for possible pregnancy?
Hello MO, yes the light flow is likely happening because of the anti-biotics.
Hi I last had sex sept 30 but I’m taking the lady pill, I got my period oct.9 then I took antibiotic in 7 days.. now my menstruation has not yet come. It is 3 days delayed.
Hello there Lyn, the antibiotic might be the cause for this.
Hi Alison, I had my period on the 6th last month(October) due to taking the morning after pill…it usually comes on the 17th though.. now November 6 I had sex with withdrawal method but still took the morning after pill for safety reasons and due to a uti I had to start antibiotics (ciprofloxacin) today(11 November) …I’ve still not seen my period… I’m scared to bits…
Hello Mariam, the antibiotics might be the reason for your delay.