Q: I've had cluster headaches for 20 years. Out of everything I've tried, there are only three things that work. To abort a headache, I inhale pure oxygen, and without fail, it is gone in five to 10 minutes. It's a true wonder drug.

Imitrex nasal inhaler also works, but it's slower than oxygen and extremely expensive.

To prevent clusters of headaches, I take several modest doses a year of psilocybin in the form of mushroom tea. I have some minor psychedelic effects, and the next day I have a lasting sense of positive self-confidence. A 2006 study at Harvard showed significant remission of clusters in test subjects using small doses of psilocybin.

I've taken psilocybin over 50 times in the past several years. I still have cluster headaches, but they are very few, far less intense and easily stopped with oxygen. Other sufferers in my Facebook group have obtained total relief.

A: Cluster headaches produce excruciating pain so intense that the multiple attacks have been described as suicide headaches. That's in part because it is impossible to function during a bout of repeated, searing, one-sided head pain.

High-flow oxygen is a treatment of choice for cluster headaches. So are triptan-type nasal sprays (Headache, July/August 2016).

Psilocybin is a hallucinogen derived from mushrooms. The Food and Drug Administration considers it a Schedule I drug, meaning that it has no currently accepted medical use and a high potential for abuse. That said, some studies suggest that psilocybin may be beneficial against these killer headaches (Neurology, June 27, 2006; Journal of Psychoactive Drugs, November-December 2015).

Q: I read on your website that you should not drink coffee within one hour of taking a thyroid pill. My endocrinologist disagrees with you. He said I can have coffee right after taking levothyroxine, though I still should wait 45 minutes before eating breakfast.

Since I started taking this medication 15 months ago, my thyroid level has remained the same even though I drink coffee right after taking my pill. Am I just lucky, or is the warning wrong?

A: Years ago, Italian researchers demonstrated that coffee interferes with the absorption of levothyroxine pills such as Synthroid (Thyroid, March 2008). A different formulation, Tirosint, isn't affected by coffee, although it is pricey (Expert Opinion on Drug Delivery, July 2014).

The most important principle for taking levothyroxine is consistency. Taking it exactly the same way every day allows the physician to adjust your dose to your needs.

Q: I crossed the line a month ago from normal blood sugar to Type 2 diabetes and was put on metformin. I hate taking drugs. What can you tell me about metformin?

A: Metformin is one of the oldest and most well-studied diabetes drugs. It is inexpensive and effective. It also may have anti-cancer activity. The most common complication is digestive distress, including diarrhea.

Q: I crave cornstarch every day. I've been consuming a box of Argo starch for the past three days.

I have had this problem for more than a year, but lately it is out of control. I know one side effect is weight gain. Can you help me with this addiction, for lack of a better word?

A: Cravings for plain cornstarch or other "non-nutritive substances" such as uncooked rice or clay are termed "pica." This often is a consequence of iron deficiency (Expert Review of Hematology, November 2016).

Ask your doctor to test you for anemia. Taking an iron supplement to reverse the deficiency often eliminates the craving.

Q: What are the pros and cons of prolotherapy for knee osteoarthritis? I am not ready for knee replacement surgery, but my knees make it hard for me to exercise.

A: Prolotherapy has been around for decades. It involves injecting sugar water (dextrose), salt water (saline) or some other substance, such as platelet-rich plasma, into or around the joint. The theory is that this process creates localized targeted inflammation that leads to natural repair and joint stabilization. This treatment usually is not covered by insurance, and out-of-pocket costs can be hundreds of dollars.

Q: I am a retired medical provider with a suggestion. Dry eyes are caused in part by age-related changes in our tear films. The outer oily layer thickens and blocks the meibomian glands that make it. As a result, they don't secrete it as readily, and it's not available to stabilize the water layer. Consequently, the tear film evaporates too easily.

Applying warm tap water compresses for three to four minutes while gently massaging the eyelids will soften those oils in the glands. Then the glands secrete more oil, which helps stabilize the tear film. The warm compresses also increase blood flow to the lids to help them heal.

This should be done three times a day for two weeks, then twice a day for two weeks, and then every morning.

A: Warm compresses are a classic treatment for dry eyes caused by meibomian gland dysfunction. You are right that when these oil-secreting glands get plugged, the tear film deteriorates.