DEAR DR. ROACH: I am on blood thinners, so I am unable to take ibuprofen or naproxen for pain. Do you know of anything I can take to help with pain?

— K.B.

ANSWER: The body has two ways of clotting blood: the blood clotting factors and platelets, which are special blood clotting cells.

Warfarin (Coumadin), like newer agents such as dabigatran (Pradaxa) or rivaroxaban (Xarelto), work as anticoagulants, blocking proteins that help clot the blood. They don’t actually “thin” the blood; that would mean a change in viscosity. Clotting factors are needed for a mature, effective blood clot.

Aspirin and NSAID drugs, like ibuprofen or naproxen (Aleve and others), affect platelets, the specialized blood cells that start clotting the blood when necessary. If both the platelet system and the factor system are decreased due to medication (or underlying clotting disorder), then the risk for abnormal bleeding goes up. This does not mean people can never take aspirin or NSAIDs if they are on a medication to reduce clotting risk, but it does mean that a careful evaluation must be done, based on a person’s unique circumstances, to determine the safety of doing so. In other words, your doctor should be able to tell you how often, if ever, you can take these over-the-counter pain relievers.

If you can’t take any, then acetaminophen (Tylenol) is usually the safest bet. However, too much acetaminophen can increase the effect of warfarin (measured by your INR level).

DEAR DR. ROACH: My sister is having a problem with severe pressure in her head. She went to a neurologist and was diagnosed with arthritis in her head. He is investigating whether it has gone into her spine. Can a person get arthritis in the head?

— P.W.

ANSWER: “Arthritis” comes from the Greek word “arthron” meaning “joint,” and “-itis,” which always means “inflammation.” So, arthritis is inflammation of the joints. Inflammation has five cardinal findings, which are still learned by medical students in Latin: calor (warmth), rubror (redness), dolor (pain), tumor (swelling) and functio laesa (loss of function). People often use the term “arthritis” when they mean they have joint pain without inflammation, which is really called arthralgia. Still, “arthritis” is commonly used to describe joint pain even if strictly speaking, it’s arthralgia.

The skull itself has only one joint that typically gets arthritis or arthralgia. This is the temporal-mandibular joint, where the jawbone attaches. The neck, however, has many joints, and the cervical spine is a common place for arthralgia and arthritis. The skull rests on the first vertebra of the neck, called the atlas, or C1. The atlas, in turn, rests on the axis, the second cervical vertebra (C2). While arthritis can happen at the skull/neck joints (also called the craniovertebral junction), my experience is that joint pain is much more common lower in the cervical spine.

DEAR DR. ROACH: Is chlamydia easy to cure with antibiotics?

— Anon.

ANSWER: Although there are several different species of the bacterium Chlamydia, including an important one that causes pneumonia, I assume you mean chlamydia trachomatis, the kind that causes genital disease in both men and women.

Yes, it can be easily cured. The cure rate with either of the first-line antibiotics, doxycycline or azithromycin, is 96% to 100%. The hard part is making the diagnosis, since the infection can be clinically silent, but can still be passed on.

Unfortunately, unless all partners are treated simultaneously, it’s possible to be reinfected.

Gonorrhea is often present at the same time as chlamydia, and it’s important that testing for that infection also be done.

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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 Dr., Orlando, FL 32803.