I'm also allergic to citric acid; also am either allergic to or intolerant of sodium in any form which rules out stool softener and milk of magnesia. The latest thing I've been trying is Miralax (polyethelene glycol); I only take 1/4 the recommended amount once a day and it helps. Any more than 1/4, it just increases gas. It takes about 20 hours for it to work, though.

Good luck to you.