There is no official warning against drinking milk for people who have arthritis and a milk allergy, and the body of research on the connection is insufficient right now. There are however numerous accounts of people who have discovered for themselves that cutting out cow's milk or other potential allergens from the diet has made a remarkable difference in rheumatoid arthritis symptoms.
Could the medical community and patients benefit from more studies? Most certainly. The more patients who experience a reduction in symptoms after going on a dairy-free diet and who discuss this potential link with their physicians, the more the medical community may ask for studies. After all, if something as simple as recognizing a milk intolerance can help some arthritis sufferers, what medical professional wouldn't want their patient to benefit from this knowledge?
There have been some studies over the years on the milk-arthritis link. Of several studies recorded in the US National Library of Medicine archives, one 1986 study, "Food-induced (allergic) arthritis. Inflammatory arthritis exacerbated by milk," found that yes, drinking milk can worsen joint pain and inflammation. Although the study was conclusive, only one women was tested. Another study in 1987, "Immune complexes in food-induced arthralgia," found that patients with food allergies who also suffered from arthritis showed a great improvement when allergens were removed from the diet. In a more recent study done in 2006, "General or personal diet: individualized model for diet challenges to patients for rheumatoid arthritis," it was found that dietary manipulations in the form of the removal of food allergens, "may effect the disease activity for selected RA patients."