In this U.S. Navy handout, sailors aboard the amphibious assault ship USS Kearsarge (LHD 3) move move pallets of supplies on the flight deck during a replenishment-at-sea with the fast combat support ship USNS Supply (T-AOE 6) for continuing operations in Puerto Rico on September 28, 2017. Kearsarge is assisting with relief efforts in the aftermath of Hurricane Maria.

If you're thinking about emptying out your pantry and clearing out your closet to donate to Puerto Rico disaster relief, think again. The help may actually be more harmful.

The Voluntary Organizations Active in Disaster recommends cash donations, telling visitors to its website that most organizations aren't able to handle a deluge of material goods in the early stages of a recovery effort. That's largely because of challenges with storage and sorting. Donations often spoil while they are waiting to be distributed.

Regine Webster, a vice president at the Center for Disaster Philanthropy, said material goods often create "a second disaster" for organizers who are already struggling to set up logistics in a challenging environment.

"There are systems in place to get people what they need," she said. But often after a large disaster, heavy winter coats will be sent to relieve people in warm climates and other snafus. "It's really awful."

However, cash has been pouring into relief efforts for the areas ravaged by hurricanes in the last few weeks, including parts of Texas, Florida and, especially, the Caribbean and Puerto Rico.

Through Thursday, $295.3 million has been collected for Harvey relief, with $98.3 million for Irma and $21.9 million for Maria and more coming in daily, according to the Foundation Center.

The Center for International Disaster Information has a list of 55 ways people can convert their material items in to cash that can be donated — including having a garage sale and donating the proceeds or giving generously to local food banks and shelters.

A number of long-running organizations, including Unicef, the American Red Cross and Save the Children are taking donations, according to USAID's website devoted to the hurricanes, and there are some recently organized efforts.

United for Puerto Rico is a disaster relief effort put together by the First Lady of Puerto Rico, Beatriz Rossello. It is sponsored by a number of large companies, including Banco Popular, Coca-Cola, Burger King, Walmart, Walgreens, JetBlue and Bacardi.

In addition, Global Giving is a crowdfunding site aiming to raise $5 million for Puerto Rico and the Caribbean, so far it has $2.7 million from 22,803 people. It matches donations to local charities and groups in 170 countries.

The One America Appeal is headed up by all the living former U.S. presidents. The organization sprang up in response to Harvey, but expanded to include relief for Irma and Maria.

Money for Harvey will go to the hurricane relief fund in Houston, and for Irma to the Florida Disaster Fund. For Maria, money will go to United for Puerto Rico and the Fund for the Virgin Islands.

The Center for Disaster Philanthropy began four funds in response to recent disasters including the earthquake in Mexico. Its Atlantic Hurricane Season Recovery Fund was set up to address rebuilding over the medium and long term in the storm-torn regions.