DEAR DR. ROACH: If I take Viagra on an empty stomach, eat dinner one hour later, then have sex 45 minutes after that, will Viagra work very effectively in this situation? — Anon.

ANSWER: Although the manufacturer says you can take sildenafil (Viagra) with or without food 30 minutes to four hours before sexual activity, I went to a conference where the speaker said he gives this easy-to-remember advice: Take the pill at 6, have dinner at 7, and you’re good until midnight. Of course, you can change the times around, but my patients have reported that this is good advice.

Viagra and similar drugs do not work for everybody. Sexual function is not so simple that a pill will fix it in all cases. But the recommended timing around food gives Viagra in particular its best chance to work. I also prefer to start with higher doses, since you really want the first use to be effective: If it’s not effective the first time, a lot of men won’t even bother trying it again.

Similar medications, such as tadalafil (Cialis), are not affected by food the way Viagra is.

DEAR DR. ROACH: Both my insulin (Toujeo, for Type 2 diabetes) and my EpiPen (allergy to shellfish) require storage at moderate temperatures, up to only 86 F, but I will be traveling in a very hot part of Africa next month (the AVERAGE temperature during the day is going to be 95 F). What should folks do under these circumstances? — E.A.E.

ANSWER: The epinephrine in your EpiPen is very stable, chemically. After a year of storage at 40 degrees Celsius (104 F), 94 percent of the original epinephrine in the ampule was still active.

Insulin is another issue, and I don’t have as clear an answer. Some insulins are listed as safe to store up to body temperature (37 C, 98.6 F). However, other insulins will break down at that temperature, and there is no reliable way of telling whether the insulin you have is still good after heat exposure. While we await the release of more heat-stable insulins (at least one has been developed), your best bet is to keep the insulin as cool as possible for as long as possible, since the insulin degrades faster at higher temperatures. Use an insulated container with ice packs or at least cold water bottles to keep the insulin near its optimal storage condition.

If that is impossible, you should be prepared to adjust the dose of insulin. One study of insulin by five different manufacturers showed that the effectiveness decreased by 14 to 18 percent after a month at 37 C. A rough guess is that the insulin might be 3 to 5 percent less effective for each week it is stored at the average temperature you note, so you may need slightly higher doses of insulin.

DEAR DR. ROACH: The 71-year-old woman from a recent column who finds sticking her finger to test her blood glucose too painful to be willing to do it likely was never told that while sticking her finger at the tip IS painful, sticking at the side of the end of the finger is barely painful, if at all. I find myself surprised that those who stick fingers for blood at the hospital don’t seem to know this either. Shame on them. — R.S.

ANSWER: There are more nerve endings at the tip of the finger, so that is more painful for most. There often is better blood flow on the sides as well. Thank you for writing with this reminder.

READERS: The booklet on COPD explains both emphysema and chronic bronchitis, the two elements of COPD, in detail. Readers can obtain a copy by writing:

Dr. Roach

Book No. 601

628 Virginia Dr.

Orlando, FL 32803

Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow 4-6 weeks for delivery.

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 request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from www.rbmamall.com.