# 25 weeks pregnant and chlorphenamine



## gem4aid

hi i am on chlorphenamine 4mg tablets three times a day( but i have reduced it down to one a day as i was worried about taking them) for urticaria i don't know what causes it. the doctor told me they have been used for years and best to take and didn't tell me to stop at any time or to go back but when i read the info leaflet it said not to take in the third trimester, can you tell me what the side affects are and should i be going back to the doctors or stopping them?
obviously i do not want to harm the baby but at the same time i do not know how i will cope without taking them as it affects my hands and feet(i cant wear shoes when its really bad).

any advice greatly appreciated
Gemma


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## mazv

Hi Gemma,

Although drugs can sometimes be prescribed and used during pregnancy they are rarely licensed for use (not really possible to do clinical trials on pregnant women) For this reason most information leaflets will state that there is no information on use in pregnancy and the drugs shouldn't be taken unless on doctors advice (or words to that effect)

The UK centre (NTIS) that gathers information about drug use in pregnancy gives the following advice about the use of chlorphenamine:_

Conclusions
Due to the extensive use of chlorphenamine in pregnancy it is considered one of the antihistamines of choice. The available published data together with data from NTIS do not indicate an increased risk of fetal toxicity after exposure to chlorphenamine during pregnancy. (updated Feb 2009)_

It doesn't differentiate between use in the different trimester of pregnancy either. I'm not aware of any difference in effect when taking the drug at different times either, the side effects are the same. The main issue with chlorphenamine is that is is very sedative. Personally I would follow the advice from your doctor, as they have assesed your individual circumsatnces and decided that you should continue to treat the urticaria. Do give them a call though if you want to discuss this further.
Best wishes
Maz x


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## gem4aid

thank you for your reply
the leaflet info is actually different in my new box which said most you have plus "unknown risks to the unborn baby when taken during the last 3 months of pregnancy. chlorphenamine may result in reactions in the newborn or premature babies. 
do you know what reactions in the newborn they might be and how long before birth would i have to stop, to not have an affect on her at birth.


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## mazv

Hi gem,

Sorry not to get back to you last week, don't have access to the specialist text books at home and not had time at work in the past few days to post.

I've checked the national teratology information service advice (collates info from exposed pregnancies in the UK and also searches all the reports from around the world) and also both the UK and USA drugs in pregnancy text books. I can find nothing about chlorphenamine having been proven to cause problems in the third trimester   

There is a report relating two other sedating antihistamines to causing a withdrawal reaction in the newborn; possibly causing tremor, paridoxical excitation. The sedating antihistmines can also cause antimuscarinic side effects (dry mouth, urinary retention, constipation) and are not generally used in babies under 1 month. I can only think that this precaution is also being extended to all drugs belonging to this class and this is why the leaflets for chlorphenamine state caution in the third tri.

It takes about 10 days to clear from the body so you'd need to stop it about 2 weeks before delivery for you both to be clear of it before delivery. You should however discuss with your GP if you are considering stopping this as it could have a detrimental effect on your own health.

Hope this helps
Maz x


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