Do Antihistamines Affect Your Period?

In our latest question and answer, the pharmacist discusses how antihistamines could theoretically affect your menstrual period and hormone levels.

Dec 19, 2017

Student27 asked

About a year ago I developed severe chronic hives. I’ve been dealing with them for months and we can’t seem to get them to go away. I had an allergy tests performed along with changing my diet. The allergy specialist didn’t diagnose me with anything other then saying it could be idiopathic and to just take Zyrtec. I have noticed within the last month or so that when I take medicine my stomach hurts really bad. I take a probiotic and Zyrtec twice a day along with Benadryl when needed. Lately I noticed that when I took Benadryl it wasn’t doing anything so I started to take more then I the dosage at a time on the bottle. Also, my period is 2 going on 3 weeks late and I’ve been reading online that extreme amounts of antihistamines can mess with your hormonal levels and stopping your period. Is this correct? Also, would the overuse of the antihistamines be causing my stomach to hurt so bad? I am lost with what to do. My chronic hives aren’t getting any better.


Antihistamine medications, such as Benadryl, Claritin and Zyrtec, are not known to cause significant changes in hormone levels and are not associated with changes in the menstrual cycle. 

Having said that, there is certainly a relationship between histamine and certain hormones (e.g. estrogen and progesterone) in our bodies. How antihistamines ultimately affect these hormones and the menstrual period, is not well known. There doesn't appear to any significant changes, but there have been some studies that do touch on the relationship between histamine, hormones and the menstrual cycle.

We know that estrogen stimulates the release of histamine from mast cells and lessens the amounts of histamine clearing enzymes in the body. In addition, histamine stimulates the production of estradiol. It is commonly agreed among experts that histamine is important for normal ovulation, lactation, uterine environment and the contractile activity of uterus. 

While we know that histamine is an important compound for numerous bodily processes, there is a distinct lack of information in regard to antihistamine medication causing any change to the menstrual cycle. It certainly could be possible based on what we know about histamine, but again, information is lacking. In the clinical trials for many antihistamine drugs, there have been infrequent reports of certain side effects such as:

  • Dysmenorrhea
  • Breast Pain
  • Intermenstrual bleeding

Zyrtec Package Insert

One of the only studies that have tested the effect of an antihistamine on menses found that the administration of chlorpheniramine (a first generation antihistamine) lessened total blood loss during menses. There was no discussion regarding a delay in menses or ovulation.

As long as you not taking more than the recommended dose of antihistamines, it is unlikely that they would be significantly be affecting your menstrual cycle. Taking more than the recommended dose, or combining several different ones may or may not be affecting you, there just isn't any definitive information.

If you are looking for alternative treatments for resistant hives, be sure to speak with your doctor. The most studied antihistamines for treatment of hives (urticaria) include:

  • Xyzal (Over The Counter)
  • Zyrtec (Over The Counter)
  • Allegra (Over The Counter)
  • Hydroxyzine (Prescription)
  • Singulair (Prescription - 'off label indication')
  • Xolair (Prescription)

Ready for a more personal experience with your meds?