I took cold medicine so now I feel all loopy and tired.
I feel too tired to do anything because of my cold medicine.
This cold medicine makes me feel too tired to do anything else.
I took cold medicine so now I feel all loopy and tired.
I feel too tired to do anything because of my cold medicine.
This cold medicine makes me feel too tired to do anything else.
I'm sorry I feel so tired but I took some cold medicine and that did it.
I don't feel like doing anything because I took some cold medicine.
I need to rest because the cold medicine makes me drowsy.
I took cold medicine so now I feel all loopy and tired.（風邪薬を飲んだので、眠くてボーッとする）
I feel too tired to do anything because of my cold medicine.（風邪薬のせいでだるくて何もできない）
This cold medicine makes me feel too tired to do anything else.（この風邪薬を飲むとだるくて何もできなくなる）
I'm sorry I feel so tired but I took some cold medicine and that did it.（ごめんなさい、体がだるいんです。風邪薬を飲んだせいです）
I don't feel like doing anything because I took some cold medicine.（風邪薬を飲んだせいで、何もしたくないです）
I need to rest because the cold medicine makes me drowsy.（この風邪薬を飲むと眠くなるので少し休まないといけない）
I'm pretty drowsy from the medication I took and I don't feel like doing anything.
My cold medicine made me very sleepy and I'm just going to stay in.
I don't feel like doing anything. My cold medicine made me really drowsy.
You can use "cold medicine", "medication" and "medicine" interchangeably in this situation. You can also divide this idea into two sentences like I did in the third example or make compound sentences like I did in the first and second. You can also add emphasis with word like "very", "really" and "pretty".
By saying that you feel drowsy, implies that the medicine you have taken makes you feel lazy and tired. Furthermore, you don't have the energy to do activities.
I feel drowsy' は、薬のせいでだるくて眠いというニュアンスです。加えて、活動をする気力がないことをいいます。
I'm a little knocked up on cold medicine, can I rest for a minute?
I feel slightly drowsy after taking my cold medicine, I'm not up to whatever you guys have planned.
I'm going to have to call in a rain check, the cold medicine is making me drowsy.
The first repose is something I would only use with my friends and family members, as being knocked up has some negative connotations, but it can mean dosed with drugs (both medicinal and not). At the end of the first response the "can I rest for a minute," implies that one needs a moment to recuperate and feel okay before proceeding. The second and third responses I'll use with anyone. A rain check is just like saying I'm going to have to postpone or cancel for today.
一つ目の回答は、私なら友達や家族にしか使いません。というのは、"knocked up" というフレーズにはネガティブな含みがあります。「薬（医療用であってもそうでなくても）を飲んだ」という意味もありますが。
一つ目の回答の最後 "can I rest for a minute?" は、先に進む前に少し休ませて欲しいというニュアンスです。
二つ目と三つ目の回答は誰に対しても使えます。
"A rain check" は「今日はキャンセル［延期］しないといけない」といった意味です。
The side effect of taking cold medication is drowsiness - so I'm not up for doing anything right now
If your cold medicine makes you feel drowsy and you do not feel ,like doing anything, then you could give the listener one of the sample explanatiomns above.
To be up for (doing something) - To be available, motivated and enthusiastic to do something.
"I'm not up for playing tennis right now as I've pulled a muscle in my leg.."
風邪薬のせいで頭がボーッとしてやる気が起きないなら、上記の文の一つが使えます。
To be up for (doing something) - ～をやる気満々で
"I'm not up for playing tennis right now as I've pulled a muscle in my leg.."
（脚を肉離れしているから、今はテニスはできない）
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