Lunar gravity provided relief from problems caused by weightlessness
Nearly every Apollo astronaut suffered from space adaptation syndrome during the weightless trip from the Earth to the moon. The most common symptom was sinus congestion:
With only two exceptions, the crewmen for all eleven flights experienced a fullness-of-the-head feeling upon orbital insertion. The persistence of the feeling was variable, lasting from 4hours to 3days.
Apollo Program Summary Report, section 8.2.3
Some astronauts had facial edema:
Another condition resulting from the lack of gravitational pull was puffiness of the face. This symptom was specifically reported by the crews of the Apollo 11, 12, 13 and 15 missions; however, it probably occurred on all the flights.
Apollo Program Summary Report, section 8.2.3
Eight astronauts had nausea, but this was entirely limited to the trans-lunar coast. There was no nausea on the moon.
Four crews reported soreness of the back caused by weightlessness. Stretching and exercising alleviated the problem before they reached the moon.
The medications used in each Apollo flight are covered in another answer. Some of the medications addressed the sinus congestion and sleep issues addressed in this answer.
One they reached the gravity of the moon, these problems disappeared:
The Command Module Pilot apparently experienced no difficulty in adapting to weightlessness; but the Lunar Module Pilot reported that his sensation of head-fullness lasted 3 days. In addition, the Lunar Module Pilot experienced slight giddiness which precluded rapid head or body movements. This sensation disappeared shortly after landing on the lunar surface and did not recur on returning to the zero-gravity environment.
Apollo 15 Mission Report
Food, drinking water, and waste disposal were problematic in zero gravity, but improved considerably with the moon's gravity:
All crews reported that food preparation and waste management functions were easier to perform in the lunar gravity field as compared to the zero-gravity conditions of flight. On the lunar surface, for example, food bags conveniently stayed where they were placed. Also, air bubbles in water, permanent in zero gravity, automatically floated out of the in-suit drink container and the hydrated food bags.
Apollo Program Summary Report, section 6.1.2.7
As far as negative health effects caused by the lunar environment, inhaling moon dust was a danger:
A troublesome and ever-present problem that was corrected only partly during lunar surface missions was that of dust. On all missions, large amounts of floating dust were present in the lunar module cabin after insertion into lunar orbit. The Apollo 12 crew noted that dust made breathing without helmets both difficult and hazardous.
Apollo Program Summary Report, section 6.1.2.7
The worst health effect on the moon was sleep deprivation. The lunar module was an uncomfortable place to sleep:
The Apollo 11 crewmen reported that their sleep on the lunar surface was a complete loss because of light leakage into the cabin, excessive cabin noise, and an uncomfortably cool cabin temperature. The Apollo 12 crewmen, who slept in their pressure suits in sleeping hammocks, noted that the cabin noise was loud, but not loud enough to prevent adequate sleep. The Apollo 14 crew reported that very little sleep was obtained on the surface, primarily because they were uncomfortable in the suits, and recommended that crews remain unsuited during sleep periods. When this recommendation was adopted for Apollo 15 and subsequent missions, crews obtained adequate sleep. Also, a correlation was noted between the ability of the crews to sleep soundly and their increasing confidence in the proper operation of lunar module systems, based on proven performance.
Apollo Program Summary Report, section 6.1.2.7
The Apollo 14 lunar astronauts could not sleep because they were paranoid that the lunar module would tip over!
The [Apollo 14] lunar module crewmen received little, if any, sleep between their two extravehicular activity periods. The lack of an adequate place to rest the head, discomfort of the pressure suit, and a 7-degree starboard list of the lunar module on the lunar terrain were believed responsible for the lack of sleep. The crewmen looked out the window several times during the sleep period for reassurance that the lunar module was not starting to tip over.
Apollo Program Summary Report, section 8.2.4(h)
This last item is technically caused by the moon's gravity. But in general, the moon's gravity had only positive health effects.
Russian cosmonaut Valery Polyakov spent nearly 438 consecutive days aboard the Mir space station, from January 1994 to March 1995. He therefore holds the record for longest single human spaceflight — and perhaps set another one for wobbliest legs when he finally touched down.-- I cannot attest to what data the Russians kept, but it may be a place to start. (SOURCE). $\endgroup$