The effect of Artificial CO₂-bathing was compared with that of placebo bathing on patients with rheumatoid arthritis (RA). A large tablet containing sodium bicarbonate and citric acid, which is called Bub, was used to make CO₂ gas as it dissolves in water bath. A placebo tablet, which is quite same in the appearance, has the substrate only and makes no gas. So the trial was performed by single blind method.
Forty two RA patients (definite or classical) were tested by single bathing and other 40 RA patients, by serial bathing of 30 days (once a day). After a single bathing grip strength of the patients increased significantly in both groups, but more significantly in Bub group (p<0.01 vs p<0.05). The joint tenderness also reduced significantly after a single bathing in both groups, almost equally. However plasma β endorphin levels were little changed after single bathing in both groups.
By serial bathing of 30 days, Lansbury's activity index, ADL score, and pain score were all changed insignificantly in each group. However Bub group showed a tendency to improve in the 3 parameters, whereas placebo group did a tendency to deteriorate.
From the above results it was considered that artificial CO₂-bathing may exert more beneficial effects on RA patients, as compared with plain water bathing.

The effect of octylphthalide (OP) bathing was compared with placebo bathing on patients with rheumatoid arthritis (RA).
A liquid containing octylphthalide was dissolved in water of 40°C at a concentration of 10ppm. A liquid which has quite similar appearance and perfume to the above was used as a placebo. Double blind controlled study tests were performed.
Twenty patients (10 for OP bathing and 10 for placebo bathing) were tested by single bathing, 33 other patients (16 patients for OP bathing and 17 for placebo bathing), by serial bathing for 30 days (once a day).
After a single bathing, while grip strengths, tender joints scores, and 20m walking time improved significantly in the OP bathing group, only tender joint scores and 20m walking time improved significantly in the placebo bathing group.
After serial bathing for 30 days, tender joint scores improved significantly in the OP bathing group, but no improvement was observed in the placebo bathing group. The above results suggest that OP bathing may be beneficial for RA patients, but further study may be needed.