I have been prescribed Mirtazapine for my intestinal issues. How long should I take it?

Q. What are the chances of interactions between Mirtazapine, Escitalopram, Flupenthixol, and Nortryptyline?

Answered by
Dr. Saraswat Kumarshri Shriniwas
and medically reviewed by iCliniq medical review team.
This is a premium question & answer published on Dec 26, 2022 and last reviewed on: Sep 25, 2023

Hello doctor,

I moved to a new country four years back. I used to eat at hotels or restaurants. As a result, I had frequent food poisoning episodes. I got food poisoning more than 20 times in two years. Each time it was treated with a course of antibiotics. For the last three years, I have completely shifted to home-cooked food. Attempts were made to correct this issue by using probiotics and fiber supplements. Also, a non-absorbing antibiotic called Rifaximin was tried to see if there was an improvement but in vain. The doctor said I have some problems in my intestine. For the functional intestinal issue, treatment using Mirtazapine 7.5 mg has been recommended. I want to try Mirtazapine and see if there is an improvement. Please answer the following: If I am getting relief, what is the course duration for Mirtazapine 7.5 mg? Will mild cases like mine recover from this issue? I am currently on Escitalopram 15 mg, Flupenthixol 5 mg, and Nortryptyline 25 mg for stress. Even though I have stress, I did not feel any digestive discomfort proportional to stress in the past. Is it possible to add Mirtazapine 7.5 mg to this regimen? Will there be any unwanted interactions?



Welcome to icliniq.com.

It seems that frequent gastrointestinal infections have triggered irritable bowel syndrome. I would like to tell you the following: Mirtazapine is used for IBS (irritable bowel syndrome) and shows good results. It is quite safe too. Initially, take it for three months. Then, you can stop and check if there is a further need to continue. IBS can go into remission or exacerbation, and the duration of treatment is decided upon the duration of an active illness. Yes, I think you will recover from this completely. I would suggest you continue taking probiotics. Mirtazapine goes well with Escitalopram. They act in conjunction, and it boosts the antidepressant effect of Escitalopram. No significant interactions with Nortriptyline 25 mg or Flupenthixol 0.5 mg are seen. Consult a specialist doctor, discuss with them, and take medications with their consent.

Thank you.

Thank you doctor for the reply,

I started taking the tablet Mirtazapine 7.5 mg three days ago. I was advised to start with half a tablet of 7.5 mg at night for ten days and then continue with 7.5 mg. The result is positive. The stool has become rigid and well-formed to a good extent. I would like to understand if IBS is an issue with nerves connected to the intestine. Has the brain become sensitive to signals from nerves connected to the intestines?



Welcome back to icliniq.com.

I am glad to know that you are doing well. The mechanism of IBS is still a medical mystery. The brain and gut are connected bidirectionally through nerves, hormones, and immune pathways. This is known as the brain-gut axis. In IBS, the brain-gut axis is malfunctioning, but it is unknown where or what exactly the issue is.

Thank you.

Hi Doctor,

1) Can I take Escitalopram 15mg , Flupenthixol .5mg ,Nortryptyline 25mg and Mirtazapine 7.5 mg at night together ?.

( just to avoid dose two times a day )

2) Does this combination cause serotonin syndrome ?.

2) Which exercise is good for mental health . Aerobic or weight training ?.

3) Are there some food items which are good for mental health when consumed on a daily basis ?.

4) Is there a diet plan good for mental health ?.
# Hello George,

1) Yes, there is no problem in taking them together at one time at night.

2) theoretically, combining antidepressants could lead to Serotonin syndrome but in practice, antidepressants are combined very often and serotonin syndrome is still rare.

Taking into consideration the medicines and the doses that you are taking, i wouldn't worry much about serotonin syndrome. It wouldn't be wise to discontinue a working combination of medicines just to avoid the theoretical rare risk of serotonin syndrome.

3)All exercise is good for mental health. But if you have time and energy for just one, choose aerobic exercise. You can also do weight training 2-3 times a week and aerobic exercise other days to keep it interesting. As i said, any exercise done for 30-45 minutes daily boosts mental health.

4)Fresh fruits, vegetables, nuts contain anti oxidants which promote mental health. Dark chocolate is good too.

5)simple carbohydrates like sugars aren't good for mental health. They cause tiredness and lethargy. A diet with sufficient protein (1mg/kg body weight) is needed for good and sustained energy levels.

6)Like wise, your diet should include complex carbohydrates and fats in your meal too. All nutrients in adequate proportions are needed for good functioniong of the brai

Hope this helps,

Hi Doc


Does Mirtazapine has a potential to increase anxiety initially ?. If so how long will it last?

After 10 days of taking 1/2 of 7.5 mg tablet , I am taking 7.5mg from last 5 days.

I feel a spike in anxious thoughts(Disturbing my concentration) from last 3 days.
# Hello George,

No, mirtazapine is not known to increase anxiety initially.
Infact, it is used to control anxiety at the beginning of treatment.

Regarding your increase in disturbing thoughts, are they obsessive in nature ( repeatative, disturbing, unwanted and intrusive, which are difficult to control).? some people report increase in obsessions with mirtazapine.

Any new change in symptoms, if it is transient and because of a medicine, it should usually go away in 1 to 2 weeks after increasing the dosage.
If it doesn't, then it might not be transient.

Yes. It is exactly what you describe.

Obsessive in nature ( repetitive, disturbing, unwanted and intrusive, which are difficult to control focused on friction with people that happened in the past.)
# Hello,
OK, some medicines like mirtazapine / olanzapine can cause increase in obsessions.
Sometimes, it is transient, sometimes, it stays.

My recommendation would be -
if you can bear it for few more days, wait and see if it goes away.
If it doesn't reduce after 7-15 days of increasing dosage , then you might need to discontinue the medicine.

I will wait for couple of days and see if there is a reduction.

If so I will continue till the 15th day and then further continue based on the outcome.

I had a hope that if it is due to medicine then it goes away but as per your latest comment the issue may stay.

I am hoping for the best.
# Hello,

Yes, it is difficult to predict in advance, if it stays or goes.your plan sounds reasonable.

I hope that it goes away and you are able to continue the medicine without any issue.

Regards and best wishes,
I continued 7.5 mg for straight 7 days and it didn't show any signs of reduction in anxiety and I stopped it.

Now I feel better. I hope the induced obsessive thoughts will resolve on its own with the current medications.

I understand that there are other medicines used by gastroenterologist for the same purpose.

One such recommendation is Chlordiazepoxide HCI & Clidinium Bromide.

I am yet to receive the dosage from gastro.

1) Is Chlordiazepoxide the only benzodiazepine anxiolytic which calms down the Vagus nerve and relieves the symptoms of IBS.

2) What is your opinion on trying Chlordiazepoxide HCI & Clidinium Bromide.

3) I red about a feature of mind called placebo and nocebo. can you shed some details on it ?.
# Hello George,
Ya, I think the obsessions should wane out gradually in a matter of time.

Coming to your questions
1) no, all benzodiazepines help ibs by reducing anxiety.
Chlordiazepoxide is preferred because its mild, not very sedating and least habit forming. Besides, it comes in one tablet in combination with clidinum bromide.

2)it helps a lot of people with ibs. Older practitioners use it a lot with good results. And its quite safe too.

3)placebo effect is when a pill/procedure makes you feel better because of your expectations about it. The effect is not due to any active pharmaceutical ingredient but because of your own mind.
Nocebo is getting an adverse effect from such a neutral non active drug.
Psychological phenomena like pain are most responsive to placebos.

In my experience, these are transient effects and don't show long term benefit for psychiatric / physical disorders.

Hopefully, the new medicine will help your ibs. Best wishes.
The recommended dosage is Librax 3 times daily 30 mins before food for 1 week and then follow up.

1) I hope this combination goes well with my current medications.
# Hello, yes, that's the recommended dosing initially. After a while, you'll be able to reduce it.

1)Yes, it will go smoothly along with escitalopram, Nortriptyline and Flupenthixol.

I wish it works for you.

I have completed Librax 3 times daily 30 mins before food for 3 weeks.

I don't see a positive response. The stool does not have a rigid consistency. The only thing which I feel is increased sleep ( 9 - 10 hours).

With Mirtazapine it was positive ( stool has rigid consistency ) but unfortunately it gave obsessions as side effect.

1) Why does Mirtazapine slows down over active gut motility. is it because of the antagonism at 5HT3 receptor ?.

2) Is 5HT3 receptor only found in brain and vagus nerve ?.

3) can we use a pure 5HT3 antagonist drug instead of Mirtazapine.

4) I came to know that Ramosetron(5HT3 antagonist) 5mcg is effective for stool consistency and rigidity .

Can I trial it and note the response. Does it have a potential to spike obsessive thoughts like mirtazapine ?.

5) Does 5HT3 antagonists antagonize the serotonin receptors both in brain and vagus nerve?.

6) Please let me know your thoughts if there is a better alternative.
# Hello George,

let me answer your queries -

1) mirtazapine has anti cholinergic and anti histamine action in addition to 5HT3 antagonism. anticholinergic agents are known to slow down gut motility.

2)5HT3 receptors are found in gut and are related to gastro enteric system.

3)we can try

4) Ramosetron is used for IBS and can certainly be tried. It is unlikely to cause spike in obsessive symptoms. Those symptoms of mirtazapine are probably due to anti histamine action.

. 5) 5HT3 antagonists block 5HT3 receptors involved in gut motility. So, they could help you.

I would recommend increasing dietary fibre as first resort. Salads could help a lot. If diet is insufficient in fibre, you can always take supplements of fibre. We need about 30 gms of dietary fibre daily.

Hope, this helps.


From last two years I am regularly taking fibre supplement . I take Isaphagula Husk powder 5 gms in morning and 5gms in the night.

In addition to that I take 1 probiotic capsule. I am experiencing good effects of fibre. I am able to pass more stool in a single go. Also i believe my gastrointestinal immunity has improved as I am able to recover from eating non fresh food from restaurants without any extra medicines. Most of the times I eat home cooked meals.

1) In order to switch to Ramosetron , I need to taper Librax(3 times daily) right ?.

May I know the schedule for tapering.

2) I hope I am not disturbing you with follow ups. If possible I need to get back my tummy back to normal.
# Hello,

Yes, it is better if you taper off librax.

Whenever you decide to stop,
I would recommend taking it once a day for 7 days and then quitting it.

Hope this helps,. Regards

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