This is one of those posts that probably won’t interest regular readers but I’m posting so it’s indexed in search engines for people who may be looking for people’s experiences on the subject. I will preface this by stressing that I am not a doctor and this is purely an anecdotal account. Do not base any medical decisions on reading this story; please consult your doctor.
It appears I had a bad reaction to pseudoephedrine (Sudafed) today, possibly as a consequence of being on levothyroxin (Synthroid) for hypothyroidism. The drug information warned about possible drug interactions for those with thyroid disease, but I’d taken Sudafed many times before without a problem.
I couldn’t find too much online, but it appears, at least according to anecdotal accounts, that people on Synthroid can develop a sensitivity to the stimulant qualities of pseudoephedrine. I took a dose yesterday without a problem. This morning I took 120 mg pseudoephedrine[1] in the morning (a 12-hour Zyrtec-D pill[2]), shortly after taking 88 mcg Synthroid on an empty stomach. By about 11am (approximately; I wasn’t keeping very good track of time), I was shivering badly like I had a high fever and felt alternately hot and cold. My heart rate started to increase and I felt physically wired at the same time I was mentally exhausted.
My resting heart rate got up to around 90-100 bpm, I became extremely jittery, and my roommate tells me my speech was jumpy and slightly disjointed (well, to be perfectly honest, she says I looked like a heroin addict when she came home, which was around 2pm). I felt hopped up while at the same time I wanted nothing more than to go to sleep. For a while I just sat shaking in a corner. I would describe the physical sensation as being a caged-animal type of feeling while still having no energy to do anything at all. I was slightly mentally unfocused but didn’t feel (mentally) out of control at all; in fact I had enough concentration to do some online research and discuss the situation rationally over the phone with family, come to the conclusion it probably was a drug interaction, and decide I probably wasn’t in danger and just needed to let the drug leave my system. In fact, I should note that I had no “high” feeling or “positive” mental effect at all; the whole thing was a manifestly uncomfortable experience.
My roommate reminded me to eat and drink around 2:30pm, and by a little after 4pm the wired feeling began to dissipate. By 4:30pm I was feeling much better, albeit tired, and the physical jitters and shaking had stopped.
Things I’ve learned from this story: (1) I should probably avoid pseudoephedrine in the future, (2) I don’t ever want to try meth.
- From reading the backs of the drug packs in the drug store, I believe this was a fairly high dose as pseudoephedrine doses go—the “regular” Sudafed (a 4-6 hour pill) had only 30 mg of pseudoephedrine, 1/4 the 120 mg dose that both the “maximum strength” Sudafed and the Zyrtec-D (both 12-hour pills) were listed to have.↵
- A combination of Zyrtec and Sudafed had been recommended by my doctor for the miserable cold I’m currently suffering from as it may be complicated by allergies; Zyrtec-D combines an antihistamine with pseudoephedrine as a decongestant.↵
