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
I had a sex with my bf after that 4 days I have uti and take antibiotic then this week I thought I have menstruation because this week I have menstruation but until now I have no menstruation
Hi Arah, antibiotics can change your menstrual cycle. The period delay you are having might be because of those antibiotics. Regards
Hi, I am so worried please help me. July 19 was the end of my period. My boyfriend and I had sex for the first time july 21 and 22. August first week I was diagnosed with uti. I was prescribed co amoxiclav 1g for 1 week. Until now August 23 my period and its still did not come. I am so confused
Hi Aya, antibiotics can surely change your menstrual cycle. The period delay you are having might be because of that medicine you are taking. Regards
Hi, I am a 15 year old virgin. My period is usually on time. A few weeks before, I was advised by my doctor to take antibiotics. And my period is 6 days late now. Is it a normal thing??
Hi Angela, high potency antibiotics can change your menstrual cycle and it is a normal thing that happens to almost everyone taking antibiotics. However, you should always ask your doctor about the side effects of the antibiotics that he/she recommends you. Regards
Hi, I was on Mentronidazole 500mg / 2x 7days. Last dose was 8/15. I was supposed to start my period on 8/16, I’m 3 days late, should I be worried or is this common?
Hi Emily, high potency antibiotics can surely change your menstrual cycle and it is a common condition that happens to nearly every women taking antibiotics. Regards
Hi i was on metronidazole 400 3 a day can this effect my progesterone level
Hi, Metronidazole can affect your progesterone level. High doses of this drug can decrease your progesterone level. Moreover, always ask your doctor about the possible side effects of the drugs he/she prescribes. Regards
I started antibiotics day 4 of starting a new pack of birth control. The night before I started the antibiotics I had unprotected sex with my boyfriend. Could I be pregnant? I was supposed to get my period today but it is a no show
Hi Chantel, Taking high potency antibiotics can delay your period. It depends on the type of antibiotics your doctor recommended you. Your delayed period might be the side effect of that antibiotics you are taking. You should ask your doctor about the side effects of the antibiotics he is prescribing you. Regards
Hello! I was advised to take antibiotics 3x a day because of my toothache. then it was supposed to be my period. The first day was normal but then i only got spotting on the second day. could i be pregnant?
Hi Ahyer,
Antibiotics can affect you menstrual cycle and can cause spotting. However, there are some women who experience no effect of the antibiotic. If you usually have regular period, it is unlikely that you are pregnant. You may want to talk with your doctor for further advise.
Hi Ahyer, high-potency antibiotics can affect your period. The spotting might be because of the antibiotics. You should ask the doctor about the side effects of those antibiotics.
I was in the ER two weeks ago with a laceration in my knee and had to get stitches. I then was on antibiotics and pain medication for a week. I was supposed to get my period 4 days ago and still haven’t gotten it. Could that be from the medications and/or the injury? Thanks.
Hi Noah, periods can be fluctuated by the effects of antibiotics. This might be because of antibiotics in your case. I would recommend you to ask your about the side effects of those medications you are taking. Regards.
I am on cloxacillin for edema and a diabetes .I just started periods and they are excessively heavy.Could this mean anything?Please help….
Hi I’m dobby
1) May 22, 2016 had period and starting to taking pills on the first day of period
2) May 28 and 29 2016 making love with my bf
3) June 15 to 19 admitted due to Urinary truck infection
4) June 17, 2016 I’m having my period
Question can I be pregnant?
hi, i was advised to take antibiotics 3x a day because of my toothache. then it was supposed to be my period but then i only got spotting. could i be pregnant?
Hello Alliyah, You should get your periods in a few days. However if the periods are delayed then get it evaluated from your doctor. Apart from medications and pregnancy, there are many other reasons for a delayed period. The other causes are hormonal imbalance like in PCOS (Polycystic ovarian syndrome), stress, obesity, malnutrition, anemia, hypothyroidism, illness, etc.
It is very difficult to precisely confirm a diagnosis without examination. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps.
Regards
I’m currently on day 10 of my period – usual length for me is 3 days. I’m currently on Metronidazole and Doxycycline – could this explain my lengthy bleed?
Hi, my period ended June 14th, and supposed to start from the 5th this month. However, I have gotten a stomach infection with high fever some June 18 and lasted for a week. I was prescribed antibiotics 4 tabs * 7 days by the doctor. But I had got some clots from the 2nd day(June.24) of taking these antibiotic pills. The amount of clots and blood was like a loonie and lasted around five days. I still not have my period come this month as it supposed to be. I wonder would that five days of clots be the my period, which supposed to come at the beginning of July? Your answer and opinion will be a huge help to me. thanks.
Good day Joi!
the medication obviously is the reason why you had clots for those periods. However it might not be your usually monthly flow. You could just observe yourself and see if your monthly flow will show up. If it doesn’t you could visit the doctor to ask for the contraindications of the antibiotics used.
regards
Hello Joi, High potency medications can surely cause spotting, apart from your monthly cycle.
Apart from medications, there are many other reasons for a delayed period. The other causes are hormonal imbalance like in PCOS (Polycystic ovarian syndrome), stress, obesity, malnutrition, anemia, hypothyroidism, illness, etc. You should get your period soon. If you don’t get it, you are requested to consult your doctor. I sincerely hope that helps. Take care.
I got a chest infection and started using antibiotics the week my period was due. I am a few days late!
Will being sick be the reason for the delay in my period???
antibiotics can cause the delay of your cycle. please read this post for more information
Hi, my physician prescribed amoxycilin for me because I have a cold. One day after, I saw my period. Should I stop? Though I still have cold.
Hi I’ve been taking yaz but had to start taking antibiotics (erythromycin) during the last active pill in the pack. today I took my last inactive pill but I haven’t gotten my period. Is this OK? I haven’t had sex since I started the antibiotics.
Hi Tan,
If you’re taking antibiotics for an illness, it can affect your menstrual cycle. Most women experience no change, but a heavy course of antibiotics can delay your period.
Although most antibiotics probably do not affect birth control pills, some antibiotics may decrease their effectiveness.
Make sure to talk to your doctor or pharmacist if you should use additional birth control methods while using this antibiotic.