Antihistamines are still worth trying for interstitial cystitis
Dear Dr. Roach: You recently wrote that the antihistamine Zyrtec might be helpful for interstitial cystitis (IC). A recently published review found no benefit. Would you readdress your opinion? D.M.
Answer: The review that you sent looked at the same studies I did to make its recommendation, but they came to a different conclusion. While the data are the same, I framed my answer a little differently.
The study showed that in patients with IC, the use of antihistamines helped some people – 31% improved with an antihistamine, while 20% improved on a placebo. But the studies could not conclude with 95% confidence that the results may have been due to chance. (They were only 75% sure.) The study only included 61 people, which makes proving a benefit difficult.
It is possible that with a larger trial, the benefit would be powerful enough to reject with a high level of certainty the hypothesis that antihistamines are no better than a placebo. I should note that the same study failed to show a significant benefit of Elmiron, which had 34% of its subjects improve compared to 18% with a placebo. Elmiron costs over $1,000 a month and has a small risk of serious retinal disease with long-term use. Larger studies did confirm the benefit of Elmiron, although it was even lower than the benefit seen in the smaller study.
The review authors chose to say that there is no benefit to antihistamines, but that’s not exactly true. Thirty-one percent of people benefitted, but this was not a large enough proportion to meet statistical significance. Thus, there is no statistically proven benefit, but these small trials ought to at least lead to larger studies to further elucidate whether there really is a benefit.
In the meantime, clinicians have to consider the possible benefits against the known harms of the treatment. In the case of an over-the-counter oral antihistamine, even a small possibility of benefit seems worth a try, since the potential for harm is miniscule. (Similarly, I received letters from IC sufferers who noted that probiotics and turmeric helped them. There are no strong data to support their use, but they are pretty safe and unlikely to cause harm.)
Finally, the main objective for me was not to say that antihistamines are a great treatment, but to bring awareness to a condition that many people aren’t even aware they have. This is a condition that many doctors aren’t comfortable diagnosing, and it also causes terrible symptoms for many patients.
Dear Dr. Roach: A recent column was about a person who fainted when getting blood drawn. My problem is that no one seems to be able to put an IV into me. Any ideas?
L.L.
Answer: Some people just don’t have very prominent veins, and they can be hard to find. Phlebotomy nurses are the best at finding veins and getting IVs in. As an intern, I feared those few times when the phlebotomy nurse couldn’t find a vein, as it usually meant putting an intravenous catheter into a central vein, which is a minor surgical procedure done at the bedside with some risks.
Now, infrared vein finders and bedside ultrasounds have made putting in IVs much easier, and the requirement for central veins is much less common.
Since I wrote that column, the most common additional suggestions I received were to take oneself to a happy place in your mind during the blood draw and to ask the phlebotomist to use your hand rather than your arm.
Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Drive, Orlando, FL 32803.