Do Vitamin B12 Injections Make You Drowsy?
For the last couple of days I’ve been feeling a bit drowsy.
- The physio at my fitness class possibly noticed it on Friday.
- I certainly had a good siesta on Friday afternoon.
- This morning I went back to bed after the Ocado delivery at 06:30 and slept for an hour.
Google AI gave this answer to my question.
Cyanocobalamin is a form of vitamin B12 that is used to increase vitamin B12 levels. It is available in a variety of forms over the counter as a supplement and by prescription as an injection or nasal spray. Some common side effects may include headache, feeling weak or tired, and nausea.
I certainly didn’t have any headache or nausea. But then I rarely have the first and only have the second, when I see Donald Trump or Vladimir Putin on the television.
According to the BBC, we have been having unusually low atmospheric pressure for this time of year.
So I also asked Google AI if low atmospheric pressure can make you drowsy.
Google AI gave this answer to my question.
Yes, low atmospheric pressure can make you drowsy. This is because low pressure systems, often associated with stormy or cloudy weather, can lead to decreased sunlight exposure, which can disrupt the body’s natural sleep-wake cycle (circadian rhythm) and increase melatonin production, the hormone that promotes sleep. Additionally, low pressure can reduce oxygen saturation, potentially causing fatigue.
As my now-retired GP felt I was badly affected by low atmospheric pressure, I’ll go along with that!
As that GP and myself felt that low atmospheric pressure drew water out of my body and made me dehydrated, I asked Google a supplementary question – Does dehydration make you drowsy?
Google AI gave this answer to my question.
Yes, dehydration can definitely make you feel drowsy. When your body is dehydrated, it doesn’t have enough fluids to function optimally, which can lead to fatigue and drowsiness. Dehydration can also cause a drop in blood pressure, which can reduce blood flow to the brain, further contributing to feelings of tiredness and sleepiness, according to A.Vogel UK.
I’ll go along with that.
Conclusion
Did the combination of the B12 injection and the low atmospheric pressure combine to make me unusually drowsy?
It’s certainly a possibility.
The more I ask Dr. Google questions, that he passes to his computerised assistant, the more I like and trust the system.
The Anonymous Widower 
I take a B12 50 mcg Cyanocobalamin every morning and haven’t noticed anything good or bad from it but my last blood test said i was low so take it.
Comment by Nicholas Lewis | August 2, 2025 |
In 1997, a blood test showed I was low in B12. This led to being diagnosed as coeliac. Addenbrooke’s said I should have B12 injections and I’ve not missed one in nearly thirty years.
In the US, B12 injections are given as a quack remedy for stroke.
Doctors say, I made a remarkable recovery from my stroke. Was it the B12 injections?
Before 2011, when I lived in Suffolk, I generally ate Liver once a week. But that is difficult in London.
Comment by AnonW | August 2, 2025 |
I have a B12 injection every three months. Without it tiredness comes about. Alcohol can dehydrate. I am largely off alcohol. When nearing the injection time I naturally do not like drinking alcohol, having no appeal. Peroni Zero I find tastes about the same as the real thing, so why drink alcohol.
Comment by John | August 4, 2025 |